| Message ID | 20230113205518.206306-2-sjg@chromium.org |
|---|---|
| State | New |
| Headers | show |
| Series | [v6,1/2] Correct typo in dt-doc-validate command | expand |
Hi Rob, On Fri, 13 Jan 2023 at 13:58, Simon Glass <sjg@chromium.org> wrote: > > U-Boot has some particular challenges with device tree and devices: > > - U-Boot has multiple build phases, such as a Secondary Program Loader > (SPL) phase which typically runs in a pre-SDRAM environment where code > and data space are limited. In particular, there may not be enough > space for the full device tree blob. U-Boot uses various automated > techniques to reduce the size from perhaps 40KB to 3KB. It is not > always possible to handle these tags entirely at build time, since > U-Boot proper must have the full device tree, even though we do not > want it to process all nodes until after relocation. > - Some U-Boot phases needs to run before the clocks are properly set up, > where the CPU may be running very slowly. Therefore it is important to > bind only those devices which are actually needed in that phase > - U-Boot uses lazy initialisation for its devices, with 'bind' and > 'probe' being separate steps. Even if a device is bound, it is not > actually probed until it is used. This is necessary to keep the boot > time reasonable, e.g. to under a second [..] Unfortunately I still don't have the hang of this schema validation. I would like to do this: $ dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate -m test.dtb test.dtb: /some-device: failed to match any schema with compatible: ['vendor,soc1-ip'] but I don't get any errors when I manage test/bootphases.dts e.g. with misnamed properties. I thought I had this working, but that was back in November. What am I doing wrong? Regards, Simon
Hi Rob, On Thu, 19 Jan 2023 at 08:28, Rob Herring <robh@kernel.org> wrote: > > On Wed, Jan 18, 2023 at 4:05 PM Simon Glass <sjg@chromium.org> wrote: > > > > Hi Rob, > > > > On Wed, 18 Jan 2023 at 13:34, Rob Herring <robh@kernel.org> wrote: > > > > > > On Fri, Jan 13, 2023 at 2:58 PM Simon Glass <sjg@chromium.org> wrote: > > > > > > > > U-Boot has some particular challenges with device tree and devices: > > > > > > > > - U-Boot has multiple build phases, such as a Secondary Program Loader > > > > (SPL) phase which typically runs in a pre-SDRAM environment where code > > > > and data space are limited. In particular, there may not be enough > > > > space for the full device tree blob. U-Boot uses various automated > > > > techniques to reduce the size from perhaps 40KB to 3KB. It is not > > > > always possible to handle these tags entirely at build time, since > > > > U-Boot proper must have the full device tree, even though we do not > > > > want it to process all nodes until after relocation. > > > > - Some U-Boot phases needs to run before the clocks are properly set up, > > > > where the CPU may be running very slowly. Therefore it is important to > > > > bind only those devices which are actually needed in that phase > > > > - U-Boot uses lazy initialisation for its devices, with 'bind' and > > > > 'probe' being separate steps. Even if a device is bound, it is not > > > > actually probed until it is used. This is necessary to keep the boot > > > > time reasonable, e.g. to under a second > > > > > > > > The phases of U-Boot in order are: TPL, VPL, SPL, U-Boot (first > > > > pre-relocation, then post-relocation). ALl but the last two are optional. > > > > > > > > For the above reasons, U-Boot only includes the full device tree in the > > > > final 'U-Boot proper' build. Even then, before relocation U-Boot only > > > > processes nodes which are marked as being needed. > > > > > > > > For this to work, U-Boot's driver model[1] provides a way to mark device > > > > tree nodes as applicable for a particular phase. This works by adding a > > > > tag to the node, e.g.: > > > > > > > > cru: clock-controller@ff760000 { > > > > bootph-all; > > > > compatible = "rockchip,rk3399-cru"; > > > > reg = <0x0 0xff760000 0x0 0x1000>; > > > > rockchip,grf = <&grf>; > > > > #clock-cells = <1>; > > > > #reset-cells = <1>; > > > > ... > > > > }; > > > > > > > > Here the "bootph-all" tag indicates that the node must be present in all > > > > phases, since the clock driver is required. > > > > > > > > There has been discussion over the years about whether this could be done > > > > in a property instead, e.g. > > > > > > > > options { > > > > bootph-all = <&cru> <&gpio_a> ...; > > > > ... > > > > }; > > > > > > > > Some problems with this: > > > > > > > > - we need to be able to merge several such tags from different .dtsi files > > > > since many boards have their own specific requirements > > > > - it is hard to find and cross-reference the affected nodes > > > > - it is more error-prone > > > > - it requires significant tool rework in U-Boot, including fdtgrep and > > > > the build system > > > > - is harder (slower, more code) to process since it involves scanning > > > > another node/property to find out what to do with a particular node > > > > - we don't want to add phandle arguments to the above since we are > > > > referring, e.g., to the clock device as a whole, not a paricular clock > > > > - the of-platdata feature[2], which converts device tree to C for even > > > > more constrained environments, would need to become aware of the > > > > /options node > > > > > > > > There is also the question about whether this needs to be U-Boot-specific, > > > > or whether the tags could be generic. From what I can tell, U-Boot is the > > > > only bootloader which seriously attempts to use a runtime device tree in > > > > all cases. For this version, an attempt is made to name the phases in a > > > > generic manner. > > > > > > > > It should also be noted that the approach provided here has stood the test > > > > of time, used in U-Boot for 8 years so far. > > > > > > > > So add the schema for this. This will allow a major class of schema > > > > exceptions to be dropped from the U-Boot source tree. > > > > > > > > This being sent to the mailing list since it might attract more review. > > > > A PR will be sent when this has had some review. That is why the file > > > > path is set up for https://github.com/devicetree-org/dt-schema rather > > > > than the Linux kernel. > > > > > > > > [1] https://u-boot.readthedocs.io/en/latest/develop/driver-model/index.html > > > > [2] https://u-boot.readthedocs.io/en/latest/develop/driver-model/of-plat.html > > > > > > > > Signed-off-by: Simon Glass <sjg@chromium.org> > > > > --- > > > > > > > > Changes in v6: > > > > - Use 'bootph' instead of 'phase' > > > > - Use | instead of , in patternProperties > > > > - Drop mention of 40KB for device-tree size > > > > - Rework description of handling of parent nodes > > > > - Use separate properties for each boot phase > > > > - Update validation example at the top of bootphases.dts > > > > > > > > Changes in v5: > > > > - Fix instructions to run test > > > > - Update binding title > > > > - Use 'phase-' instead of 'phase,' > > > > > > > > Changes in v4: > > > > - Drop some unnecessary context from the commit message > > > > - Explain why parent nodes do not automatically inherit their children's > > > > tags > > > > - Rename the tags to use a phase,xxx format, explaining each one > > > > > > > > Changes in v3: > > > > - Fix an incorrect schema path in $id > > > > > > > > Changes in v2: > > > > - Expand docs to include a description of each tag > > > > - Fix some typos and unclear wording > > > > > > > > dtschema/lib.py | 5 +++ > > > > dtschema/schemas/bootph.yaml | 86 ++++++++++++++++++++++++++++++++++++ > > > > test/bootphases.dts | 22 +++++++++ > > > > 3 files changed, 113 insertions(+) > > > > create mode 100644 dtschema/schemas/bootph.yaml > > > > create mode 100644 test/bootphases.dts > > > > > > > > diff --git a/dtschema/lib.py b/dtschema/lib.py > > > > index c7b6cb9..95a4f10 100644 > > > > --- a/dtschema/lib.py > > > > +++ b/dtschema/lib.py > > > > @@ -493,6 +493,11 @@ def fixup_node_props(schema): > > > > schema['properties'].setdefault('status', True) > > > > schema['properties'].setdefault('secure-status', True) > > > > schema['properties'].setdefault('$nodename', True) > > > > + schema['properties'].setdefault('bootph-pre-sram', True) > > > > + schema['properties'].setdefault('bootph-verify', True) > > > > + schema['properties'].setdefault('bootph-pre-ram', True) > > > > + schema['properties'].setdefault('bootph-some-ram', True) > > > > + schema['properties'].setdefault('bootph-all', True) > > > > > > > > keys = list() > > > > if 'properties' in schema: > > > > diff --git a/dtschema/schemas/bootph.yaml b/dtschema/schemas/bootph.yaml > > > > new file mode 100644 > > > > index 0000000..275c4da > > > > --- /dev/null > > > > +++ b/dtschema/schemas/bootph.yaml > > > > @@ -0,0 +1,86 @@ > > > > +# SPDX-License-Identifier: BSD-2-Clause > > > > +# Copyright 2022 Google LLC > > > > +%YAML 1.2 > > > > +--- > > > > +$id: http://devicetree.org/schemas/bootph.yaml# > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > > + > > > > +title: Boot-phase-specific device nodes > > > > + > > > > +maintainers: > > > > + - Simon Glass <sjg@chromium.org> > > > > + > > > > +description: | > > > > + Some programs run in memory-constrained environments yet want to make use > > > > + of device tree. > > > > + > > > > + The full device tree is often quite large relative to the available memory > > > > + of a boot phase, so cannot fit into every phase of the boot process. Even > > > > + when memory is not a problem, some phases may wish to limit which device > > > > + nodes are present, so as to reduce execution time. > > > > + > > > > + This binding supports adding tags to device tree nodes to allow them to be > > > > + marked according to the phases where they should be included. > > > > + > > > > + Without any tags, nodes are included only in the final phase, where all > > > > + memory is available. Any untagged nodes are dropped from previous phases > > > > + and are ignored before the final phase is reached. > > > > + > > > > + The build process produces a separate executable for each phase. It can > > > > + use fdtgrep to drop any nodes which are not needed for a particular build. > > > > + For example, the pre-sram build will drop any nodes which are not marked > > > > + with bootph-pre-sram or bootph-all tags. > > > > + > > > > + Note that phase builds may drop the tags, since they have served their > > > > + purpose by that point. So when looking at phase-specific device tree files > > > > + you may not see these tags. > > > > + > > > > + Multiple tags can be used in the same node. > > > > + > > > > + Tags in a child node are implied to be present in all parent nodes as well. > > > > + This is important, since some missing properties (such as "ranges", or > > > > + "compatible") can cause the child node to be ignored or incorrectly > > > > + parsed. > > > > + > > > > + That said, at present, fdtgrep applies tags only to the node they are > > > > + added to, not to any parents. This means U-Boot device tree files often > > > > + add the same tag to parent nodes, rather than relying on tooling to do > > > > + this. This is a limitation of fdtgrep and it will be addressed so that > > > > + 'Linux DTs' do not need to do this. > > > > + > > > > + The available tags are describes as properties below, in order of phase > > > > > > described > > > > > > > + execution. > > > > + > > > > > > I think your issue testing is you need a 'select: true' here. 'select' > > > is how we test whether a schema should be applied to a node. The > > > default is to use compatible or $nodename for matching. You have > > > neither, so select is false. > > > > I feel like I have the opposite problem, in that the validation is not > > actually happening, i.e. it isn't failing with something like > > bootph-pre-sramxxx or anything else I put into the node: > > Right. Since you get the default 'select: false', your schema is never > used for validation. > > > > > I do see this: > > > > dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate -m test.dtb > > test.dtb: /some-device: failed to match any schema with compatible: > > ['vendor,soc1-ip'] > > Adding '-s test/schemas' to dt-validate should fix that error (and > probably add schema errors). dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate -s test/schemas -m test.dtb /usr/local/google/home/sjg/cosarm/dt-schema/test/schemas/bad-example.yaml: ignoring, error in schema: title /usr/local/google/home/sjg/cosarm/dt-schema/test.dtb: some-device: 'bootph-pre-sram' does not match any of the regexes: 'pinctrl-[0-9]+'
Hi Rob, On Thu, 19 Jan 2023 at 10:32, Simon Glass <sjg@chromium.org> wrote: > > Hi Rob, > > On Thu, 19 Jan 2023 at 10:21, Rob Herring <robh@kernel.org> wrote: > > > > On Thu, Jan 19, 2023 at 10:18 AM Simon Glass <sjg@chromium.org> wrote: > > > > > > Hi Rob, > > > > > > On Thu, 19 Jan 2023 at 08:28, Rob Herring <robh@kernel.org> wrote: > > > > > > > > On Wed, Jan 18, 2023 at 4:05 PM Simon Glass <sjg@chromium.org> wrote: > > > > > > > > > > Hi Rob, > > > > > > > > > > On Wed, 18 Jan 2023 at 13:34, Rob Herring <robh@kernel.org> wrote: > > > > > > > > > > > > On Fri, Jan 13, 2023 at 2:58 PM Simon Glass <sjg@chromium.org> wrote: > > > > > > > > > > > > > > U-Boot has some particular challenges with device tree and devices: > > > > > > > > > > > > > > - U-Boot has multiple build phases, such as a Secondary Program Loader > > > > > > > (SPL) phase which typically runs in a pre-SDRAM environment where code > > > > > > > and data space are limited. In particular, there may not be enough > > > > > > > space for the full device tree blob. U-Boot uses various automated > > > > > > > techniques to reduce the size from perhaps 40KB to 3KB. It is not > > > > > > > always possible to handle these tags entirely at build time, since > > > > > > > U-Boot proper must have the full device tree, even though we do not > > > > > > > want it to process all nodes until after relocation. > > > > > > > - Some U-Boot phases needs to run before the clocks are properly set up, > > > > > > > where the CPU may be running very slowly. Therefore it is important to > > > > > > > bind only those devices which are actually needed in that phase > > > > > > > - U-Boot uses lazy initialisation for its devices, with 'bind' and > > > > > > > 'probe' being separate steps. Even if a device is bound, it is not > > > > > > > actually probed until it is used. This is necessary to keep the boot > > > > > > > time reasonable, e.g. to under a second > > > > > > > > > > > > > > The phases of U-Boot in order are: TPL, VPL, SPL, U-Boot (first > > > > > > > pre-relocation, then post-relocation). ALl but the last two are optional. > > > > > > > > > > > > > > For the above reasons, U-Boot only includes the full device tree in the > > > > > > > final 'U-Boot proper' build. Even then, before relocation U-Boot only > > > > > > > processes nodes which are marked as being needed. > > > > > > > > > > > > > > For this to work, U-Boot's driver model[1] provides a way to mark device > > > > > > > tree nodes as applicable for a particular phase. This works by adding a > > > > > > > tag to the node, e.g.: > > > > > > > > > > > > > > cru: clock-controller@ff760000 { > > > > > > > bootph-all; > > > > > > > compatible = "rockchip,rk3399-cru"; > > > > > > > reg = <0x0 0xff760000 0x0 0x1000>; > > > > > > > rockchip,grf = <&grf>; > > > > > > > #clock-cells = <1>; > > > > > > > #reset-cells = <1>; > > > > > > > ... > > > > > > > }; > > > > > > > > > > > > > > Here the "bootph-all" tag indicates that the node must be present in all > > > > > > > phases, since the clock driver is required. > > > > > > > > > > > > > > There has been discussion over the years about whether this could be done > > > > > > > in a property instead, e.g. > > > > > > > > > > > > > > options { > > > > > > > bootph-all = <&cru> <&gpio_a> ...; > > > > > > > ... > > > > > > > }; > > > > > > > > > > > > > > Some problems with this: > > > > > > > > > > > > > > - we need to be able to merge several such tags from different .dtsi files > > > > > > > since many boards have their own specific requirements > > > > > > > - it is hard to find and cross-reference the affected nodes > > > > > > > - it is more error-prone > > > > > > > - it requires significant tool rework in U-Boot, including fdtgrep and > > > > > > > the build system > > > > > > > - is harder (slower, more code) to process since it involves scanning > > > > > > > another node/property to find out what to do with a particular node > > > > > > > - we don't want to add phandle arguments to the above since we are > > > > > > > referring, e.g., to the clock device as a whole, not a paricular clock > > > > > > > - the of-platdata feature[2], which converts device tree to C for even > > > > > > > more constrained environments, would need to become aware of the > > > > > > > /options node > > > > > > > > > > > > > > There is also the question about whether this needs to be U-Boot-specific, > > > > > > > or whether the tags could be generic. From what I can tell, U-Boot is the > > > > > > > only bootloader which seriously attempts to use a runtime device tree in > > > > > > > all cases. For this version, an attempt is made to name the phases in a > > > > > > > generic manner. > > > > > > > > > > > > > > It should also be noted that the approach provided here has stood the test > > > > > > > of time, used in U-Boot for 8 years so far. > > > > > > > > > > > > > > So add the schema for this. This will allow a major class of schema > > > > > > > exceptions to be dropped from the U-Boot source tree. > > > > > > > > > > > > > > This being sent to the mailing list since it might attract more review. > > > > > > > A PR will be sent when this has had some review. That is why the file > > > > > > > path is set up for https://github.com/devicetree-org/dt-schema rather > > > > > > > than the Linux kernel. > > > > > > > > > > > > > > [1] https://u-boot.readthedocs.io/en/latest/develop/driver-model/index.html > > > > > > > [2] https://u-boot.readthedocs.io/en/latest/develop/driver-model/of-plat.html > > > > > > > > > > > > > > Signed-off-by: Simon Glass <sjg@chromium.org> > > > > > > > --- > > > > > > > > > > > > > > Changes in v6: > > > > > > > - Use 'bootph' instead of 'phase' > > > > > > > - Use | instead of , in patternProperties > > > > > > > - Drop mention of 40KB for device-tree size > > > > > > > - Rework description of handling of parent nodes > > > > > > > - Use separate properties for each boot phase > > > > > > > - Update validation example at the top of bootphases.dts > > > > > > > > > > > > > > Changes in v5: > > > > > > > - Fix instructions to run test > > > > > > > - Update binding title > > > > > > > - Use 'phase-' instead of 'phase,' > > > > > > > > > > > > > > Changes in v4: > > > > > > > - Drop some unnecessary context from the commit message > > > > > > > - Explain why parent nodes do not automatically inherit their children's > > > > > > > tags > > > > > > > - Rename the tags to use a phase,xxx format, explaining each one > > > > > > > > > > > > > > Changes in v3: > > > > > > > - Fix an incorrect schema path in $id > > > > > > > > > > > > > > Changes in v2: > > > > > > > - Expand docs to include a description of each tag > > > > > > > - Fix some typos and unclear wording > > > > > > > > > > > > > > dtschema/lib.py | 5 +++ > > > > > > > dtschema/schemas/bootph.yaml | 86 ++++++++++++++++++++++++++++++++++++ > > > > > > > test/bootphases.dts | 22 +++++++++ > > > > > > > 3 files changed, 113 insertions(+) > > > > > > > create mode 100644 dtschema/schemas/bootph.yaml > > > > > > > create mode 100644 test/bootphases.dts > > > > > > > > > > > > > > diff --git a/dtschema/lib.py b/dtschema/lib.py > > > > > > > index c7b6cb9..95a4f10 100644 > > > > > > > --- a/dtschema/lib.py > > > > > > > +++ b/dtschema/lib.py > > > > > > > @@ -493,6 +493,11 @@ def fixup_node_props(schema): > > > > > > > schema['properties'].setdefault('status', True) > > > > > > > schema['properties'].setdefault('secure-status', True) > > > > > > > schema['properties'].setdefault('$nodename', True) > > > > > > > + schema['properties'].setdefault('bootph-pre-sram', True) > > > > > > > + schema['properties'].setdefault('bootph-verify', True) > > > > > > > + schema['properties'].setdefault('bootph-pre-ram', True) > > > > > > > + schema['properties'].setdefault('bootph-some-ram', True) > > > > > > > + schema['properties'].setdefault('bootph-all', True) > > > > > > > > > > > > > > keys = list() > > > > > > > if 'properties' in schema: > > > > > > > diff --git a/dtschema/schemas/bootph.yaml b/dtschema/schemas/bootph.yaml > > > > > > > new file mode 100644 > > > > > > > index 0000000..275c4da > > > > > > > --- /dev/null > > > > > > > +++ b/dtschema/schemas/bootph.yaml > > > > > > > @@ -0,0 +1,86 @@ > > > > > > > +# SPDX-License-Identifier: BSD-2-Clause > > > > > > > +# Copyright 2022 Google LLC > > > > > > > +%YAML 1.2 > > > > > > > +--- > > > > > > > +$id: http://devicetree.org/schemas/bootph.yaml# > > > > > > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > > > > > > + > > > > > > > +title: Boot-phase-specific device nodes > > > > > > > + > > > > > > > +maintainers: > > > > > > > + - Simon Glass <sjg@chromium.org> > > > > > > > + > > > > > > > +description: | > > > > > > > + Some programs run in memory-constrained environments yet want to make use > > > > > > > + of device tree. > > > > > > > + > > > > > > > + The full device tree is often quite large relative to the available memory > > > > > > > + of a boot phase, so cannot fit into every phase of the boot process. Even > > > > > > > + when memory is not a problem, some phases may wish to limit which device > > > > > > > + nodes are present, so as to reduce execution time. > > > > > > > + > > > > > > > + This binding supports adding tags to device tree nodes to allow them to be > > > > > > > + marked according to the phases where they should be included. > > > > > > > + > > > > > > > + Without any tags, nodes are included only in the final phase, where all > > > > > > > + memory is available. Any untagged nodes are dropped from previous phases > > > > > > > + and are ignored before the final phase is reached. > > > > > > > + > > > > > > > + The build process produces a separate executable for each phase. It can > > > > > > > + use fdtgrep to drop any nodes which are not needed for a particular build. > > > > > > > + For example, the pre-sram build will drop any nodes which are not marked > > > > > > > + with bootph-pre-sram or bootph-all tags. > > > > > > > + > > > > > > > + Note that phase builds may drop the tags, since they have served their > > > > > > > + purpose by that point. So when looking at phase-specific device tree files > > > > > > > + you may not see these tags. > > > > > > > + > > > > > > > + Multiple tags can be used in the same node. > > > > > > > + > > > > > > > + Tags in a child node are implied to be present in all parent nodes as well. > > > > > > > + This is important, since some missing properties (such as "ranges", or > > > > > > > + "compatible") can cause the child node to be ignored or incorrectly > > > > > > > + parsed. > > > > > > > + > > > > > > > + That said, at present, fdtgrep applies tags only to the node they are > > > > > > > + added to, not to any parents. This means U-Boot device tree files often > > > > > > > + add the same tag to parent nodes, rather than relying on tooling to do > > > > > > > + this. This is a limitation of fdtgrep and it will be addressed so that > > > > > > > + 'Linux DTs' do not need to do this. > > > > > > > + > > > > > > > + The available tags are describes as properties below, in order of phase > > > > > > > > > > > > described > > > > > > > > > > > > > + execution. > > > > > > > + > > > > > > > > > > > > I think your issue testing is you need a 'select: true' here. 'select' > > > > > > is how we test whether a schema should be applied to a node. The > > > > > > default is to use compatible or $nodename for matching. You have > > > > > > neither, so select is false. > > > > > > > > > > I feel like I have the opposite problem, in that the validation is not > > > > > actually happening, i.e. it isn't failing with something like > > > > > bootph-pre-sramxxx or anything else I put into the node: > > > > > > > > Right. Since you get the default 'select: false', your schema is never > > > > used for validation. > > > > > > > > > > > > > > I do see this: > > > > > > > > > > dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate -m test.dtb > > > > > test.dtb: /some-device: failed to match any schema with compatible: > > > > > ['vendor,soc1-ip'] > > > > > > > > Adding '-s test/schemas' to dt-validate should fix that error (and > > > > probably add schema errors). > > > > > > dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate -s > > > test/schemas -m test.dtb > > > /usr/local/google/home/sjg/cosarm/dt-schema/test/schemas/bad-example.yaml: > > > ignoring, error in schema: title > > > /usr/local/google/home/sjg/cosarm/dt-schema/test.dtb: some-device: > > > 'bootph-pre-sram' does not match any of the regexes: 'pinctrl-[0-9]+' > > > From schema: /usr/local/google/home/sjg/cosarm/dt-schema/test/schemas/good-example.yaml > > > > I pulled your 'dm' branch, ran the above command and only got the > > first expected error. > > > > I added 2 expected failing cases and got: > > $ dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate -s > > test/schemas -m test.dtb > > /home/rob/proj/dt-schema/test/schemas/bad-example.yaml: ignoring, > > error in schema: title > > bootph-all: size (4) error for type flag > > /home/rob/proj/dt-schema/test.dtb: some-device: 'bootph-pre-sram-foo' > > does not match any of the regexes: 'pinctrl-[0-9]+' > > From schema: /home/rob/proj/dt-schema/test/schemas/good-example.yaml > > /home/rob/proj/dt-schema/test.dtb: some-device: bootph-all: [[0]] is > > not of type 'boolean' > > From schema: /home/rob/proj/dt-schema/dtschema/schemas/bootph.yaml > > > > > > The error message you see seems like the change in dtschema/lib.py is > > missing. Are you picking up a non-editable installed dtschema instead > > of the local one? > > Yes that was it...a previous installation so that it ignores the local one. > > > > > If you run 'dt-mk-schema test/schemas' and find 'good-example' in the > > output, you should see all the bootph entries added to the schema. > > Yes, all good, thank you. So we can go ahead? > I just wanted to check, is there anything else needed on the Linux side, or can people start submitting .dts files with this binding now? Regards, Simon
diff --git a/dtschema/lib.py b/dtschema/lib.py index c7b6cb9..95a4f10 100644 --- a/dtschema/lib.py +++ b/dtschema/lib.py @@ -493,6 +493,11 @@ def fixup_node_props(schema): schema['properties'].setdefault('status', True) schema['properties'].setdefault('secure-status', True) schema['properties'].setdefault('$nodename', True) + schema['properties'].setdefault('bootph-pre-sram', True) + schema['properties'].setdefault('bootph-verify', True) + schema['properties'].setdefault('bootph-pre-ram', True) + schema['properties'].setdefault('bootph-some-ram', True) + schema['properties'].setdefault('bootph-all', True) keys = list() if 'properties' in schema: diff --git a/dtschema/schemas/bootph.yaml b/dtschema/schemas/bootph.yaml new file mode 100644 index 0000000..275c4da --- /dev/null +++ b/dtschema/schemas/bootph.yaml @@ -0,0 +1,86 @@ +# SPDX-License-Identifier: BSD-2-Clause +# Copyright 2022 Google LLC +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/bootph.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Boot-phase-specific device nodes + +maintainers: + - Simon Glass <sjg@chromium.org> + +description: | + Some programs run in memory-constrained environments yet want to make use + of device tree. + + The full device tree is often quite large relative to the available memory + of a boot phase, so cannot fit into every phase of the boot process. Even + when memory is not a problem, some phases may wish to limit which device + nodes are present, so as to reduce execution time. + + This binding supports adding tags to device tree nodes to allow them to be + marked according to the phases where they should be included. + + Without any tags, nodes are included only in the final phase, where all + memory is available. Any untagged nodes are dropped from previous phases + and are ignored before the final phase is reached. + + The build process produces a separate executable for each phase. It can + use fdtgrep to drop any nodes which are not needed for a particular build. + For example, the pre-sram build will drop any nodes which are not marked + with bootph-pre-sram or bootph-all tags. + + Note that phase builds may drop the tags, since they have served their + purpose by that point. So when looking at phase-specific device tree files + you may not see these tags. + + Multiple tags can be used in the same node. + + Tags in a child node are implied to be present in all parent nodes as well. + This is important, since some missing properties (such as "ranges", or + "compatible") can cause the child node to be ignored or incorrectly + parsed. + + That said, at present, fdtgrep applies tags only to the node they are + added to, not to any parents. This means U-Boot device tree files often + add the same tag to parent nodes, rather than relying on tooling to do + this. This is a limitation of fdtgrep and it will be addressed so that + 'Linux DTs' do not need to do this. + + The available tags are describes as properties below, in order of phase + execution. + +properties: + bootph-pre-sram: + type: boolean + description: | + Enable this node when SRAM is not available. This phase must set up + some SRAM or cache-as-RAM so it can obtain data/BSS space to use + during execution. + + bootph-verify: + type: boolean + description: | + Enable this node in the verification step, which decides which of the + available images should be run next. + + bootph-pre-ram: + type: boolean + description: | + Enable this node in the phase that sets up SDRAM. + + bootph-some-ram: + type: boolean + description: | + Enable this node in the phase that is run after SDRAM is working but + before all of it is available. Some RAM is available but it is limited + (e.g. it may be split into two pieces by the location of the running + program) because the program code is not yet relocated out of the way. + + bootph-all: + type: boolean + description: | + Include this node in all phases (for U-Boot see enum u_boot_phase). + +additionalProperties: true diff --git a/test/bootphases.dts b/test/bootphases.dts new file mode 100644 index 0000000..037c626 --- /dev/null +++ b/test/bootphases.dts @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: BSD-2-Clause +// Copyright 2022 Google LLC + +// An attempt to provide a device tree to validate the phase properties + +// dtc -O dtb -o test.dtb test/bootphases.dts && tools/dt-validate test.dtb + + +/dts-v1/; + +/ { + model = "none"; + compatible = "foo"; + + #address-cells = <1>; + #size-cells = <1>; + + some-device { + compatible = "vendor,soc1-ip"; + bootph-pre-sram; + }; +};
U-Boot has some particular challenges with device tree and devices: - U-Boot has multiple build phases, such as a Secondary Program Loader (SPL) phase which typically runs in a pre-SDRAM environment where code and data space are limited. In particular, there may not be enough space for the full device tree blob. U-Boot uses various automated techniques to reduce the size from perhaps 40KB to 3KB. It is not always possible to handle these tags entirely at build time, since U-Boot proper must have the full device tree, even though we do not want it to process all nodes until after relocation. - Some U-Boot phases needs to run before the clocks are properly set up, where the CPU may be running very slowly. Therefore it is important to bind only those devices which are actually needed in that phase - U-Boot uses lazy initialisation for its devices, with 'bind' and 'probe' being separate steps. Even if a device is bound, it is not actually probed until it is used. This is necessary to keep the boot time reasonable, e.g. to under a second The phases of U-Boot in order are: TPL, VPL, SPL, U-Boot (first pre-relocation, then post-relocation). ALl but the last two are optional. For the above reasons, U-Boot only includes the full device tree in the final 'U-Boot proper' build. Even then, before relocation U-Boot only processes nodes which are marked as being needed. For this to work, U-Boot's driver model[1] provides a way to mark device tree nodes as applicable for a particular phase. This works by adding a tag to the node, e.g.: cru: clock-controller@ff760000 { bootph-all; compatible = "rockchip,rk3399-cru"; reg = <0x0 0xff760000 0x0 0x1000>; rockchip,grf = <&grf>; #clock-cells = <1>; #reset-cells = <1>; ... }; Here the "bootph-all" tag indicates that the node must be present in all phases, since the clock driver is required. There has been discussion over the years about whether this could be done in a property instead, e.g. options { bootph-all = <&cru> <&gpio_a> ...; ... }; Some problems with this: - we need to be able to merge several such tags from different .dtsi files since many boards have their own specific requirements - it is hard to find and cross-reference the affected nodes - it is more error-prone - it requires significant tool rework in U-Boot, including fdtgrep and the build system - is harder (slower, more code) to process since it involves scanning another node/property to find out what to do with a particular node - we don't want to add phandle arguments to the above since we are referring, e.g., to the clock device as a whole, not a paricular clock - the of-platdata feature[2], which converts device tree to C for even more constrained environments, would need to become aware of the /options node There is also the question about whether this needs to be U-Boot-specific, or whether the tags could be generic. From what I can tell, U-Boot is the only bootloader which seriously attempts to use a runtime device tree in all cases. For this version, an attempt is made to name the phases in a generic manner. It should also be noted that the approach provided here has stood the test of time, used in U-Boot for 8 years so far. So add the schema for this. This will allow a major class of schema exceptions to be dropped from the U-Boot source tree. This being sent to the mailing list since it might attract more review. A PR will be sent when this has had some review. That is why the file path is set up for https://github.com/devicetree-org/dt-schema rather than the Linux kernel. [1] https://u-boot.readthedocs.io/en/latest/develop/driver-model/index.html [2] https://u-boot.readthedocs.io/en/latest/develop/driver-model/of-plat.html Signed-off-by: Simon Glass <sjg@chromium.org> --- Changes in v6: - Use 'bootph' instead of 'phase' - Use | instead of , in patternProperties - Drop mention of 40KB for device-tree size - Rework description of handling of parent nodes - Use separate properties for each boot phase - Update validation example at the top of bootphases.dts Changes in v5: - Fix instructions to run test - Update binding title - Use 'phase-' instead of 'phase,' Changes in v4: - Drop some unnecessary context from the commit message - Explain why parent nodes do not automatically inherit their children's tags - Rename the tags to use a phase,xxx format, explaining each one Changes in v3: - Fix an incorrect schema path in $id Changes in v2: - Expand docs to include a description of each tag - Fix some typos and unclear wording dtschema/lib.py | 5 +++ dtschema/schemas/bootph.yaml | 86 ++++++++++++++++++++++++++++++++++++ test/bootphases.dts | 22 +++++++++ 3 files changed, 113 insertions(+) create mode 100644 dtschema/schemas/bootph.yaml create mode 100644 test/bootphases.dts