| Message ID | 20230121153544.467126-1-rayyan@ansari.sh |
|---|---|
| Headers | show |
| Series | SimpleDRM: allow configuring physical width and height | expand |
On Sat, 21 Jan 2023 15:35:44 +0000, Rayyan Ansari wrote: > Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> > --- > .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ > 1 file changed, 8 insertions(+) > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check' on your patch (DT_CHECKER_FLAGS is new in v5.13): yamllint warnings/errors: dtschema/dtc warnings/errors: /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/display/simple-framebuffer.yaml: properties:width-mm: '$ref' should not be valid under {'const': '$ref'} hint: Standard unit suffix properties don't need a type $ref from schema $id: http://devicetree.org/meta-schemas/core.yaml# /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/display/simple-framebuffer.yaml: properties:height-mm: '$ref' should not be valid under {'const': '$ref'} hint: Standard unit suffix properties don't need a type $ref from schema $id: http://devicetree.org/meta-schemas/core.yaml# doc reference errors (make refcheckdocs): See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20230121153544.467126-3-rayyan@ansari.sh The base for the series is generally the latest rc1. A different dependency should be noted in *this* patch. If you already ran 'make dt_binding_check' and didn't see the above error(s), then make sure 'yamllint' is installed and dt-schema is up to date: pip3 install dtschema --upgrade Please check and re-submit after running the above command yourself. Note that DT_SCHEMA_FILES can be set to your schema file to speed up checking your schema. However, it must be unset to test all examples with your schema.
On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: > Why do you need this change? The 'simple-framebuffer' contains data on how the bootloader configured the display. The bootloader doesn't configure the display size, so this information doesn't belong here. The information should already be in the panel node, so also no point in duplicating it here. > Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> > --- > .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ > 1 file changed, 8 insertions(+)
Hi, On 1/22/23 16:36, Rob Herring wrote: > On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: >> > > Why do you need this change? > > The 'simple-framebuffer' contains data on how the bootloader > configured the display. The bootloader doesn't configure the display > size, so this information doesn't belong here. The information should > already be in the panel node, so also no point in duplicating it here. The idea is that early boot code which uses the simplefb node (no more complex display driver loaded yet) knows the panel's DPI so that it can decide if hi-dpi rendering / scaling is necessary or not. This definitely is a useful feature to have. I guess that for dt systems an alternative approach could be to add a link to the panel node to the simplefb dt-node. Regards, Hans
On 22/01/2023 15:36, Rob Herring wrote: > On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: >> > > Why do you need this change? > > The 'simple-framebuffer' contains data on how the bootloader > configured the display. The bootloader doesn't configure the display > size, so this information doesn't belong here. The information should > already be in the panel node, so also no point in duplicating it here. > >> Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> >> --- >> .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ >> 1 file changed, 8 insertions(+) Hi Rob, There is the usecase that Hans has mentioned, but I have also mentioned another usecase previously. Adding the width-mm and height-mm properties allows user interfaces such as Phosh (https://puri.sm/posts/phosh-overview/) to scale correctly to the screen. In my case, a panel node is not available and the aforementioned interface is in fact running on the SimpleDRM driver (which binds to the simple-framebuffer device). Here is the device I have tested this patch on, the Lumia 735 phone: https://wiki.postmarketos.org/images/c/c3/Lumia_735_Phosh.png Without this patch, this would appear quite small on the screen. See https://patchwork.freedesktop.org/patch/519107/?series=113053&rev=1 for some background info about this patch. Regards,
On 22/01/2023 15:31, Rob Herring wrote: > > On Sat, 21 Jan 2023 15:35:44 +0000, Rayyan Ansari wrote: >> Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> >> --- >> .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> > > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check' > on your patch (DT_CHECKER_FLAGS is new in v5.13): > > yamllint warnings/errors: > > dtschema/dtc warnings/errors: > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/display/simple-framebuffer.yaml: properties:width-mm: '$ref' should not be valid under {'const': '$ref'} > hint: Standard unit suffix properties don't need a type $ref > from schema $id: http://devicetree.org/meta-schemas/core.yaml# > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/display/simple-framebuffer.yaml: properties:height-mm: '$ref' should not be valid under {'const': '$ref'} > hint: Standard unit suffix properties don't need a type $ref > from schema $id: http://devicetree.org/meta-schemas/core.yaml# > > doc reference errors (make refcheckdocs): > > See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20230121153544.467126-3-rayyan@ansari.sh > > The base for the series is generally the latest rc1. A different dependency > should be noted in *this* patch. > > If you already ran 'make dt_binding_check' and didn't see the above > error(s), then make sure 'yamllint' is installed and dt-schema is up to > date: > > pip3 install dtschema --upgrade > > Please check and re-submit after running the above command yourself. Note > that DT_SCHEMA_FILES can be set to your schema file to speed up checking > your schema. However, it must be unset to test all examples with your schema. > I will remove the $ref property in v2, but I will also wait if there is any other feedback to address.
On Sun, Jan 22, 2023 at 05:25:38PM +0000, Rayyan Ansari wrote: > On 22/01/2023 15:36, Rob Herring wrote: > > On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: > > > > > > > Why do you need this change? > > > > The 'simple-framebuffer' contains data on how the bootloader > > configured the display. The bootloader doesn't configure the display > > size, so this information doesn't belong here. The information should > > already be in the panel node, so also no point in duplicating it here. > > > > > Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> > > > --- > > > .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > Hi Rob, > > There is the usecase that Hans has mentioned, but I have also mentioned > another usecase previously. > > Adding the width-mm and height-mm properties allows user interfaces such as > Phosh (https://puri.sm/posts/phosh-overview/) to scale correctly to the > screen. In my case, a panel node is not available and the aforementioned > interface is in fact running on the SimpleDRM driver (which binds to the > simple-framebuffer device). Why is the panel node not available? Why not add it? Presumably it is not there because you aren't (yet) using the simple-panel driver (and others that would need). But presumably you will eventually as I'd imagine turning the screen off and back on might be a desired feature. So why add a temporary DT property that's tied to your *current* kernel? The DT should not be tightly coupled to the kernel. Rob
On 23/01/2023 17:53, Rob Herring wrote: > On Sun, Jan 22, 2023 at 05:25:38PM +0000, Rayyan Ansari wrote: >> On 22/01/2023 15:36, Rob Herring wrote: >>> On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: >>>> >>> >>> Why do you need this change? >>> >>> The 'simple-framebuffer' contains data on how the bootloader >>> configured the display. The bootloader doesn't configure the display >>> size, so this information doesn't belong here. The information should >>> already be in the panel node, so also no point in duplicating it here. >>> >>>> Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> >>>> --- >>>> .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ >>>> 1 file changed, 8 insertions(+) >> >> Hi Rob, >> >> There is the usecase that Hans has mentioned, but I have also mentioned >> another usecase previously. >> >> Adding the width-mm and height-mm properties allows user interfaces such as >> Phosh (https://puri.sm/posts/phosh-overview/) to scale correctly to the >> screen. In my case, a panel node is not available and the aforementioned >> interface is in fact running on the SimpleDRM driver (which binds to the >> simple-framebuffer device). > > Why is the panel node not available? Why not add it? Presumably it is > not there because you aren't (yet) using the simple-panel driver (and > others that would need). But presumably you will eventually as I'd > imagine turning the screen off and back on might be a desired feature. It requires more than using the simple-panel driver: first the SoC side display hardware needs to be brought up, then a panel driver that implements the proper DCS initialisation sequence needs to be written (which is currently not fully known). > > So why add a temporary DT property that's tied to your *current* kernel? > The DT should not be tightly coupled to the kernel. I'm not sure what you mean by it being "tightly coupled" to the kernel. > > Rob
> Date: Tue, 24 Jan 2023 22:19:09 +0000 > From: Rayyan Ansari <rayyan@ansari.sh> > > On 23/01/2023 17:53, Rob Herring wrote: > > On Sun, Jan 22, 2023 at 05:25:38PM +0000, Rayyan Ansari wrote: > >> On 22/01/2023 15:36, Rob Herring wrote: > >>> On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: > >>>> > >>> > >>> Why do you need this change? > >>> > >>> The 'simple-framebuffer' contains data on how the bootloader > >>> configured the display. The bootloader doesn't configure the display > >>> size, so this information doesn't belong here. The information should > >>> already be in the panel node, so also no point in duplicating it here. > >>> > >>>> Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> > >>>> --- > >>>> .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ > >>>> 1 file changed, 8 insertions(+) > >> > >> Hi Rob, > >> > >> There is the usecase that Hans has mentioned, but I have also mentioned > >> another usecase previously. > >> > >> Adding the width-mm and height-mm properties allows user interfaces such as > >> Phosh (https://puri.sm/posts/phosh-overview/) to scale correctly to the > >> screen. In my case, a panel node is not available and the aforementioned > >> interface is in fact running on the SimpleDRM driver (which binds to the > >> simple-framebuffer device). > > > > Why is the panel node not available? Why not add it? Presumably it is > > not there because you aren't (yet) using the simple-panel driver (and > > others that would need). But presumably you will eventually as I'd > > imagine turning the screen off and back on might be a desired feature. > > It requires more than using the simple-panel driver: first the SoC side > display hardware needs to be brought up, then a panel driver that > implements the proper DCS initialisation sequence needs to be written > (which is currently not fully known). You don't really need a driver. You can just lookup the panel node from your simple-framebuffer driver and get the values of the properties there.
On 24/01/2023 23:19, Rayyan Ansari wrote: > On 23/01/2023 17:53, Rob Herring wrote: >> On Sun, Jan 22, 2023 at 05:25:38PM +0000, Rayyan Ansari wrote: >>> On 22/01/2023 15:36, Rob Herring wrote: >>>> On Sat, Jan 21, 2023 at 9:36 AM Rayyan Ansari <rayyan@ansari.sh> wrote: >>>>> >>>> >>>> Why do you need this change? >>>> >>>> The 'simple-framebuffer' contains data on how the bootloader >>>> configured the display. The bootloader doesn't configure the display >>>> size, so this information doesn't belong here. The information should >>>> already be in the panel node, so also no point in duplicating it here. >>>> >>>>> Signed-off-by: Rayyan Ansari <rayyan@ansari.sh> >>>>> --- >>>>> .../devicetree/bindings/display/simple-framebuffer.yaml | 8 ++++++++ >>>>> 1 file changed, 8 insertions(+) >>> >>> Hi Rob, >>> >>> There is the usecase that Hans has mentioned, but I have also mentioned >>> another usecase previously. >>> >>> Adding the width-mm and height-mm properties allows user interfaces such as >>> Phosh (https://puri.sm/posts/phosh-overview/) to scale correctly to the >>> screen. In my case, a panel node is not available and the aforementioned >>> interface is in fact running on the SimpleDRM driver (which binds to the >>> simple-framebuffer device). >> >> Why is the panel node not available? Why not add it? Presumably it is >> not there because you aren't (yet) using the simple-panel driver (and >> others that would need). But presumably you will eventually as I'd >> imagine turning the screen off and back on might be a desired feature. > > It requires more than using the simple-panel driver: first the SoC side > display hardware needs to be brought up, then a panel driver that > implements the proper DCS initialisation sequence needs to be written > (which is currently not fully known). > >> >> So why add a temporary DT property that's tied to your *current* kernel? > The DT should not be tightly coupled to the kernel. > > I'm not sure what you mean by it being "tightly coupled" to the kernel. It means that you used current Linux driver support (or lack) for some hardware as an argument for bindings. If you add later the driver, the bindings should be changed? Answer is: not. Bindings should be independent of Linux drivers, thus whatever kernel is missing now, is not an argument in favor of this property. Best regards, Krzysztof
Hello, The following patches: - Add support for configuring the width-mm and height-mm DRM mode properties in the SimpleDRM driver via Device Tree - Document these two new Device Tree properties This is useful for allowing interfaces such as Phosh to calculate proper scaling values. Changes since RFC: - Switch to using 32-bit DT property - Report errors for return values of of_property_read_u32 except -EINVAL - Calculate default value during probe - Add documentation Rayyan Ansari (2): drm/simpledrm: Allow physical width and height configuration via DT dt-bindings: display: simple-framebuffer: Document physical width and height properties .../bindings/display/simple-framebuffer.yaml | 8 +++ drivers/gpu/drm/tiny/simpledrm.c | 60 ++++++++++++++++--- 2 files changed, 59 insertions(+), 9 deletions(-)