Message ID | 20181127180349.29997-1-georgi.djakov@linaro.org |
---|---|
Headers | show |
Series | Introduce on-chip interconnect API | expand |
Hi Joe, On 11/27/18 20:35, Joe Perches wrote: > On Tue, 2018-11-27 at 20:03 +0200, Georgi Djakov wrote: >> This patch introduces a new API to get requirements and configure the >> interconnect buses across the entire chipset to fit with the current >> demand. > > trivial notes: > >> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c > [] >> +static int apply_constraints(struct icc_path *path) >> +{ >> + struct icc_node *next, *prev = NULL; >> + int ret = -EINVAL; >> + int i; >> + >> + for (i = 0; i < path->num_nodes; i++, prev = next) { >> + struct icc_provider *p; >> + >> + next = path->reqs[i].node; >> + /* >> + * Both endpoints should be valid master-slave pairs of the >> + * same interconnect provider that will be configured. >> + */ >> + if (!prev || next->provider != prev->provider) >> + continue; >> + >> + p = next->provider; >> + >> + /* set the constraints */ >> + ret = p->set(prev, next); >> + if (ret) >> + goto out; >> + } >> +out: >> + return ret; >> +} > > The use of ", prev = next" appears somewhat tricky code. > Perhaps move the assignment of prev to the bottom of the loop. > Perhaps the temporary p assignment isn't useful either. > >> +int icc_set(struct icc_path *path, u32 avg_bw, u32 peak_bw) >> +{ > [] >> + ret = apply_constraints(path); >> + if (ret) >> + pr_debug("interconnect: error applying constraints (%d)", ret); > > Ideally all pr_<foo> formats should end in '\n' > >> +static struct icc_node *icc_node_create_nolock(int id) >> +{ >> + struct icc_node *node; >> + >> + /* check if node already exists */ >> + node = node_find(id); >> + if (node) >> + goto out; >> + >> + node = kzalloc(sizeof(*node), GFP_KERNEL); >> + if (!node) { >> + node = ERR_PTR(-ENOMEM); >> + goto out; > > Generally, this code appears to overly rely on goto when > direct returns could be more readable. > >> + } >> + >> + id = idr_alloc(&icc_idr, node, id, id + 1, GFP_KERNEL); >> + if (WARN(id < 0, "couldn't get idr")) { > > This seems to unnecessarily hide the id < 0 test in a WARN > > Why is this a WARN and not a simpler > if (id < 0) { > [ pr_err(...); or WARN(1, ...); ] > >> + kfree(node); >> + node = ERR_PTR(id); >> + goto out; >> + } >> + >> + node->id = id; >> + >> +out: >> + return node; >> +} Thank you for helping to improve the code. The above suggestions make it cleaner indeed. > [] >> diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h > [] >> +/* macros for converting to icc units */ >> +#define bps_to_icc(x) (1) >> +#define kBps_to_icc(x) (x) > [] >> +#define MBps_to_icc(x) (x * 1000) >> +#define GBps_to_icc(x) (x * 1000 * 1000) >> +#define kbps_to_icc(x) (x / 8 + ((x) % 8 ? 1 : 0)) >> +#define Mbps_to_icc(x) (x * 1000 / 8 ) >> +#define Gbps_to_icc(x) (x * 1000 * 1000 / 8) > > The last 5 macros should parenthesize x Oops.. obviously i forgot to run checkpatch --strict. Will fix! BR, Georgi
On Tue, Nov 27, 2018 at 10:04 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: > > From: David Dai <daidavid1@codeaurora.org> > > Add RSC (Resource State Coordinator) provider > dictating network-on-chip interconnect bus performance > found on SDM845-based platforms. > > Signed-off-by: David Dai <daidavid1@codeaurora.org> > Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org> > --- > arch/arm64/boot/dts/qcom/sdm845.dtsi | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/arm64/boot/dts/qcom/sdm845.dtsi b/arch/arm64/boot/dts/qcom/sdm845.dtsi > index b72bdb0a31a5..856d33604e9c 100644 > --- a/arch/arm64/boot/dts/qcom/sdm845.dtsi > +++ b/arch/arm64/boot/dts/qcom/sdm845.dtsi > @@ -1324,6 +1324,11 @@ > compatible = "qcom,sdm845-rpmh-clk"; > #clock-cells = <1>; > }; > + > + qnoc: qnoc { > + compatible = "qcom,sdm845-rsc-hlos"; > + #interconnect-cells = <1>; > + }; Should we alphabetize this node above rpmhcc? > }; > > intc: interrupt-controller@17a00000 {
On Tue, Nov 27, 2018 at 12:03 PM Georgi Djakov <georgi.djakov@linaro.org> wrote: > > This patch introduces a new API to get requirements and configure the > interconnect buses across the entire chipset to fit with the current > demand. > > The API is using a consumer/provider-based model, where the providers are > the interconnect buses and the consumers could be various drivers. > The consumers request interconnect resources (path) between endpoints and > set the desired constraints on this data flow path. The providers receive > requests from consumers and aggregate these requests for all master-slave > pairs on that path. Then the providers configure each participating in the > topology node according to the requested data flow path, physical links and > constraints. The topology could be complicated and multi-tiered and is SoC > specific. > > Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org> > Reviewed-by: Evan Green <evgreen@chromium.org> [...] > +struct icc_path *icc_get(struct device *dev, const int src_id, > + const int dst_id); > +void icc_put(struct icc_path *path); > +int icc_set(struct icc_path *path, u32 avg_bw, u32 peak_bw); icc_set() is very generic, but this function isn't easily extended to other parameters than bandwidth. Perhaps icc_set_bandwidth() instead. Then when you add some other setting, you just add a new function. Of course, if you wind up with a bunch of different parameters, then you'll probably need an atomic type interface where you test all the settings together and then commit them separately in one call. But from a DT perspective, I certainly hope there are not lots of new settings folks want to add. :) Rob
Hi Greg and Evan, On 12/6/18 16:55, Greg KH wrote: > On Wed, Dec 05, 2018 at 12:41:35PM -0800, Evan Green wrote: >> On Tue, Nov 27, 2018 at 10:03 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: >>> >>> Modern SoCs have multiple processors and various dedicated cores (video, gpu, >>> graphics, modem). These cores are talking to each other and can generate a >>> lot of data flowing through the on-chip interconnects. These interconnect >>> buses could form different topologies such as crossbar, point to point buses, >>> hierarchical buses or use the network-on-chip concept. >>> >>> These buses have been sized usually to handle use cases with high data >>> throughput but it is not necessary all the time and consume a lot of power. >>> Furthermore, the priority between masters can vary depending on the running >>> use case like video playback or CPU intensive tasks. >>> >>> Having an API to control the requirement of the system in terms of bandwidth >>> and QoS, so we can adapt the interconnect configuration to match those by >>> scaling the frequencies, setting link priority and tuning QoS parameters. >>> This configuration can be a static, one-time operation done at boot for some >>> platforms or a dynamic set of operations that happen at run-time. >>> >>> This patchset introduce a new API to get the requirement and configure the >>> interconnect buses across the entire chipset to fit with the current demand. >>> The API is NOT for changing the performance of the endpoint devices, but only >>> the interconnect path in between them. >> >> For what it's worth, we are ready to land this in Chrome OS. I think >> this series has been very well discussed and reviewed, hasn't changed >> much in the last few spins, and is in good enough shape to use as a >> base for future patches. Georgi's also done a great job reaching out >> to other SoC vendors, and there appears to be enough consensus that >> this framework will be usable by more than just Qualcomm. There are >> also several drivers out on the list trying to add patches to use this >> framework, with more to come, so it made sense (to us) to get this >> base framework nailed down. In my experiments this is an important >> piece of the overall power management story, especially on systems >> that are mostly idle. >> >> I'll continue to track changes to this series and we will ultimately >> reconcile with whatever happens upstream, but I thought it was worth >> sending this note to express our "thumbs up" towards this framework. > > Looks like a v11 will be forthcoming, so I'll wait for that one to apply > it to the tree if all looks good. > Yes, it's coming. I will also include an additional fixup patch, as the sdm845 provider driver will fail to build in linux-next, due to a recent change in the cmd_db API. Thanks, Georgi
On Mon, Dec 10, 2018 at 11:18 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: > > Hi Rafael, > > On 12/10/18 11:04, Rafael J. Wysocki wrote: > > On Thu, Dec 6, 2018 at 3:55 PM Greg KH <gregkh@linuxfoundation.org> wrote: > >> > >> On Wed, Dec 05, 2018 at 12:41:35PM -0800, Evan Green wrote: > >>> On Tue, Nov 27, 2018 at 10:03 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: > >>>> > >>>> Modern SoCs have multiple processors and various dedicated cores (video, gpu, > >>>> graphics, modem). These cores are talking to each other and can generate a > >>>> lot of data flowing through the on-chip interconnects. These interconnect > >>>> buses could form different topologies such as crossbar, point to point buses, > >>>> hierarchical buses or use the network-on-chip concept. > >>>> > >>>> These buses have been sized usually to handle use cases with high data > >>>> throughput but it is not necessary all the time and consume a lot of power. > >>>> Furthermore, the priority between masters can vary depending on the running > >>>> use case like video playback or CPU intensive tasks. > >>>> > >>>> Having an API to control the requirement of the system in terms of bandwidth > >>>> and QoS, so we can adapt the interconnect configuration to match those by > >>>> scaling the frequencies, setting link priority and tuning QoS parameters. > >>>> This configuration can be a static, one-time operation done at boot for some > >>>> platforms or a dynamic set of operations that happen at run-time. > >>>> > >>>> This patchset introduce a new API to get the requirement and configure the > >>>> interconnect buses across the entire chipset to fit with the current demand. > >>>> The API is NOT for changing the performance of the endpoint devices, but only > >>>> the interconnect path in between them. > >>> > >>> For what it's worth, we are ready to land this in Chrome OS. I think > >>> this series has been very well discussed and reviewed, hasn't changed > >>> much in the last few spins, and is in good enough shape to use as a > >>> base for future patches. Georgi's also done a great job reaching out > >>> to other SoC vendors, and there appears to be enough consensus that > >>> this framework will be usable by more than just Qualcomm. There are > >>> also several drivers out on the list trying to add patches to use this > >>> framework, with more to come, so it made sense (to us) to get this > >>> base framework nailed down. In my experiments this is an important > >>> piece of the overall power management story, especially on systems > >>> that are mostly idle. > >>> > >>> I'll continue to track changes to this series and we will ultimately > >>> reconcile with whatever happens upstream, but I thought it was worth > >>> sending this note to express our "thumbs up" towards this framework. > >> > >> Looks like a v11 will be forthcoming, so I'll wait for that one to apply > >> it to the tree if all looks good. > > > > I'm honestly not sure if it is ready yet. > > > > New versions are coming on and on, which may make such an impression, > > but we had some discussion on it at the LPC and some serious questions > > were asked during it, for instance regarding the DT binding introduced > > here. I'm not sure how this particular issue has been addressed here, > > for example. > > There have been no changes in bindings since v4 (other than squashing > consumer and provider bindings into a single patch and fixing typos). > > The last DT comment was on v9 [1] where Rob wanted confirmation from > other SoC vendors that this works for them too. And now we have that > confirmation and there are patches posted on the list [2]. OK > The second thing (also discussed at LPC) was about possible cases where > some consumer drivers can't calculate how much bandwidth they actually > need and how to address that. The proposal was to extend the OPP > bindings with one more property, but this is not part of this patchset. > It is a future step that needs more discussion on the mailing list. If a > driver really needs some bandwidth data now, it should be put into the > driver and not in DT. After we have enough consumers, we can discuss > again if it makes sense to extract something into DT or not. That's fine by me. Admittedly, I have some reservations regarding the extent to which this approach will turn out to be useful in practice, but I guess as long as there is enough traction, the best way to find out it to try and see. :-) From now on I will assume that this series is going to be applied by Greg. Thanks, Rafael
On 12/10/18 13:00, Rafael J. Wysocki wrote: > On Mon, Dec 10, 2018 at 11:18 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: >> >> Hi Rafael, >> >> On 12/10/18 11:04, Rafael J. Wysocki wrote: >>> On Thu, Dec 6, 2018 at 3:55 PM Greg KH <gregkh@linuxfoundation.org> wrote: >>>> >>>> On Wed, Dec 05, 2018 at 12:41:35PM -0800, Evan Green wrote: >>>>> On Tue, Nov 27, 2018 at 10:03 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: >>>>>> >>>>>> Modern SoCs have multiple processors and various dedicated cores (video, gpu, >>>>>> graphics, modem). These cores are talking to each other and can generate a >>>>>> lot of data flowing through the on-chip interconnects. These interconnect >>>>>> buses could form different topologies such as crossbar, point to point buses, >>>>>> hierarchical buses or use the network-on-chip concept. >>>>>> >>>>>> These buses have been sized usually to handle use cases with high data >>>>>> throughput but it is not necessary all the time and consume a lot of power. >>>>>> Furthermore, the priority between masters can vary depending on the running >>>>>> use case like video playback or CPU intensive tasks. >>>>>> >>>>>> Having an API to control the requirement of the system in terms of bandwidth >>>>>> and QoS, so we can adapt the interconnect configuration to match those by >>>>>> scaling the frequencies, setting link priority and tuning QoS parameters. >>>>>> This configuration can be a static, one-time operation done at boot for some >>>>>> platforms or a dynamic set of operations that happen at run-time. >>>>>> >>>>>> This patchset introduce a new API to get the requirement and configure the >>>>>> interconnect buses across the entire chipset to fit with the current demand. >>>>>> The API is NOT for changing the performance of the endpoint devices, but only >>>>>> the interconnect path in between them. >>>>> >>>>> For what it's worth, we are ready to land this in Chrome OS. I think >>>>> this series has been very well discussed and reviewed, hasn't changed >>>>> much in the last few spins, and is in good enough shape to use as a >>>>> base for future patches. Georgi's also done a great job reaching out >>>>> to other SoC vendors, and there appears to be enough consensus that >>>>> this framework will be usable by more than just Qualcomm. There are >>>>> also several drivers out on the list trying to add patches to use this >>>>> framework, with more to come, so it made sense (to us) to get this >>>>> base framework nailed down. In my experiments this is an important >>>>> piece of the overall power management story, especially on systems >>>>> that are mostly idle. >>>>> >>>>> I'll continue to track changes to this series and we will ultimately >>>>> reconcile with whatever happens upstream, but I thought it was worth >>>>> sending this note to express our "thumbs up" towards this framework. >>>> >>>> Looks like a v11 will be forthcoming, so I'll wait for that one to apply >>>> it to the tree if all looks good. >>> >>> I'm honestly not sure if it is ready yet. >>> >>> New versions are coming on and on, which may make such an impression, >>> but we had some discussion on it at the LPC and some serious questions >>> were asked during it, for instance regarding the DT binding introduced >>> here. I'm not sure how this particular issue has been addressed here, >>> for example. >> >> There have been no changes in bindings since v4 (other than squashing >> consumer and provider bindings into a single patch and fixing typos). >> >> The last DT comment was on v9 [1] where Rob wanted confirmation from >> other SoC vendors that this works for them too. And now we have that >> confirmation and there are patches posted on the list [2]. > > OK > >> The second thing (also discussed at LPC) was about possible cases where >> some consumer drivers can't calculate how much bandwidth they actually >> need and how to address that. The proposal was to extend the OPP >> bindings with one more property, but this is not part of this patchset. >> It is a future step that needs more discussion on the mailing list. If a >> driver really needs some bandwidth data now, it should be put into the >> driver and not in DT. After we have enough consumers, we can discuss >> again if it makes sense to extract something into DT or not. > > That's fine by me. > > Admittedly, I have some reservations regarding the extent to which > this approach will turn out to be useful in practice, but I guess as > long as there is enough traction, the best way to find out it to try > and see. :-) > > From now on I will assume that this series is going to be applied by Greg. That was the initial idea, but the problem is that there is a recent change in the cmd_db API (needed by the sdm845 provider driver), which is going through arm-soc/qcom/drivers. So either Greg pulls also the qcom-drivers-for-4.21 tag from Andy or the whole series goes via Olof and Arnd. Maybe there are other options. I don't have any preference and don't want to put extra burden on any maintainers, so i am ok with what they prefer. Thanks, Georgi
Hi Greg, On 12/11/18 08:58, Greg Kroah-Hartman wrote: > On Mon, Dec 10, 2018 at 04:50:00PM +0200, Georgi Djakov wrote: >> On 12/10/18 13:00, Rafael J. Wysocki wrote: >>> On Mon, Dec 10, 2018 at 11:18 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: >>>> >>>> Hi Rafael, >>>> >>>> On 12/10/18 11:04, Rafael J. Wysocki wrote: >>>>> On Thu, Dec 6, 2018 at 3:55 PM Greg KH <gregkh@linuxfoundation.org> wrote: >>>>>> >>>>>> On Wed, Dec 05, 2018 at 12:41:35PM -0800, Evan Green wrote: >>>>>>> On Tue, Nov 27, 2018 at 10:03 AM Georgi Djakov <georgi.djakov@linaro.org> wrote: >>>>>>>> >>>>>>>> Modern SoCs have multiple processors and various dedicated cores (video, gpu, >>>>>>>> graphics, modem). These cores are talking to each other and can generate a >>>>>>>> lot of data flowing through the on-chip interconnects. These interconnect >>>>>>>> buses could form different topologies such as crossbar, point to point buses, >>>>>>>> hierarchical buses or use the network-on-chip concept. >>>>>>>> >>>>>>>> These buses have been sized usually to handle use cases with high data >>>>>>>> throughput but it is not necessary all the time and consume a lot of power. >>>>>>>> Furthermore, the priority between masters can vary depending on the running >>>>>>>> use case like video playback or CPU intensive tasks. >>>>>>>> >>>>>>>> Having an API to control the requirement of the system in terms of bandwidth >>>>>>>> and QoS, so we can adapt the interconnect configuration to match those by >>>>>>>> scaling the frequencies, setting link priority and tuning QoS parameters. >>>>>>>> This configuration can be a static, one-time operation done at boot for some >>>>>>>> platforms or a dynamic set of operations that happen at run-time. >>>>>>>> >>>>>>>> This patchset introduce a new API to get the requirement and configure the >>>>>>>> interconnect buses across the entire chipset to fit with the current demand. >>>>>>>> The API is NOT for changing the performance of the endpoint devices, but only >>>>>>>> the interconnect path in between them. >>>>>>> >>>>>>> For what it's worth, we are ready to land this in Chrome OS. I think >>>>>>> this series has been very well discussed and reviewed, hasn't changed >>>>>>> much in the last few spins, and is in good enough shape to use as a >>>>>>> base for future patches. Georgi's also done a great job reaching out >>>>>>> to other SoC vendors, and there appears to be enough consensus that >>>>>>> this framework will be usable by more than just Qualcomm. There are >>>>>>> also several drivers out on the list trying to add patches to use this >>>>>>> framework, with more to come, so it made sense (to us) to get this >>>>>>> base framework nailed down. In my experiments this is an important >>>>>>> piece of the overall power management story, especially on systems >>>>>>> that are mostly idle. >>>>>>> >>>>>>> I'll continue to track changes to this series and we will ultimately >>>>>>> reconcile with whatever happens upstream, but I thought it was worth >>>>>>> sending this note to express our "thumbs up" towards this framework. >>>>>> >>>>>> Looks like a v11 will be forthcoming, so I'll wait for that one to apply >>>>>> it to the tree if all looks good. >>>>> >>>>> I'm honestly not sure if it is ready yet. >>>>> >>>>> New versions are coming on and on, which may make such an impression, >>>>> but we had some discussion on it at the LPC and some serious questions >>>>> were asked during it, for instance regarding the DT binding introduced >>>>> here. I'm not sure how this particular issue has been addressed here, >>>>> for example. >>>> >>>> There have been no changes in bindings since v4 (other than squashing >>>> consumer and provider bindings into a single patch and fixing typos). >>>> >>>> The last DT comment was on v9 [1] where Rob wanted confirmation from >>>> other SoC vendors that this works for them too. And now we have that >>>> confirmation and there are patches posted on the list [2]. >>> >>> OK >>> >>>> The second thing (also discussed at LPC) was about possible cases where >>>> some consumer drivers can't calculate how much bandwidth they actually >>>> need and how to address that. The proposal was to extend the OPP >>>> bindings with one more property, but this is not part of this patchset. >>>> It is a future step that needs more discussion on the mailing list. If a >>>> driver really needs some bandwidth data now, it should be put into the >>>> driver and not in DT. After we have enough consumers, we can discuss >>>> again if it makes sense to extract something into DT or not. >>> >>> That's fine by me. >>> >>> Admittedly, I have some reservations regarding the extent to which >>> this approach will turn out to be useful in practice, but I guess as >>> long as there is enough traction, the best way to find out it to try >>> and see. :-) >>> >>> From now on I will assume that this series is going to be applied by Greg. >> >> That was the initial idea, but the problem is that there is a recent >> change in the cmd_db API (needed by the sdm845 provider driver), which >> is going through arm-soc/qcom/drivers. So either Greg pulls also the >> qcom-drivers-for-4.21 tag from Andy or the whole series goes via Olof >> and Arnd. Maybe there are other options. I don't have any preference and >> don't want to put extra burden on any maintainers, so i am ok with what >> they prefer. > > Let me take the time later this week to review the code, which I haven't > done in a while... > When you get a chance to review, please keep in mind that the latest version is v12 (from 08.Dec). The same is also available in linux-next with no reported issues. Thanks, Georgi