Messages in this thread Patch in this message | | | Date | Fri, 24 Nov 2023 11:12:57 +0100 | Subject | Re: [PATCH] drm/panfrost: Ignore core_mask for poweroff and sync interrupts | From | AngeloGioacchino Del Regno <> |
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Il 24/11/23 10:17, AngeloGioacchino Del Regno ha scritto: > Il 23/11/23 16:40, Boris Brezillon ha scritto: >> On Thu, 23 Nov 2023 16:14:12 +0100 >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> >> wrote: >> >>> Il 23/11/23 14:51, Boris Brezillon ha scritto: >>>> On Thu, 23 Nov 2023 14:24:57 +0100 >>>> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> >>>> wrote: >>>>>>> >>>>>>> So, while I agree that it'd be slightly more readable as a diff if those >>>>>>> were two different commits I do have reasons against splitting..... >>>>>> >>>>>> If we just need a quick fix to avoid PWRTRANS interrupts from kicking >>>>>> in when we power-off the cores, I think we'd be better off dropping >>>>>> GPU_IRQ_POWER_CHANGED[_ALL] from the value we write to GPU_INT_MASK >>>>>> at [re]initialization time, and then have a separate series that fixes >>>>>> the problem more generically. >>>>> >>>>> But that didn't work: >>>>> https://lore.kernel.org/all/d95259b8-10cf-4ded-866c-47cbd2a44f84@linaro.org/ >>>> >>>> I meant, your 'ignore-core_mask' fix + the >>>> 'drop GPU_IRQ_POWER_CHANGED[_ALL] in GPU_INT_MASK' one. >>>> >>>> So, >>>> >>>> https://lore.kernel.org/all/4c73f67e-174c-497e-85a5-cb053ce657cb@collabora.com/ >>>> + >>>> https://lore.kernel.org/all/d95259b8-10cf-4ded-866c-47cbd2a44f84@linaro.org/ >>>>> >>>>> >>>>> ...while this "full" solution worked: >>>>> https://lore.kernel.org/all/39e9514b-087c-42eb-8d0e-f75dc620e954@linaro.org/ >>>>> >>>>> https://lore.kernel.org/all/5b24cc73-23aa-4837-abb9-b6d138b46426@linaro.org/ >>>>> >>>>> >>>>> ...so this *is* a "quick fix" already... :-) >>>> >>>> It's a half-baked solution for the missing irq-synchronization-on-suspend >>>> issue IMHO. I understand why you want it all in one patch that can serve >>>> as a fix for 123b431f8a5c ("drm/panfrost: Really power off GPU cores in >>>> panfrost_gpu_power_off()"), which is why I'm suggesting to go for an >>>> even simpler diff (see below), and then fully address the >>>> irq-synhronization-on-suspend issue in a follow-up patchset. >>>> --->8--- >>>> diff --git a/drivers/gpu/drm/panfrost/panfrost_gpu.c >>>> b/drivers/gpu/drm/panfrost/panfrost_gpu.c >>>> index 09f5e1563ebd..6e2d7650cc2b 100644 >>>> --- a/drivers/gpu/drm/panfrost/panfrost_gpu.c >>>> +++ b/drivers/gpu/drm/panfrost/panfrost_gpu.c >>>> @@ -78,7 +78,10 @@ int panfrost_gpu_soft_reset(struct panfrost_device *pfdev) >>>> } >>>> gpu_write(pfdev, GPU_INT_CLEAR, GPU_IRQ_MASK_ALL); >>>> - gpu_write(pfdev, GPU_INT_MASK, GPU_IRQ_MASK_ALL); >> >> We probably want a comment here: >> >> /* Only enable the interrupts we care about. */ >> >>>> + gpu_write(pfdev, GPU_INT_MASK, >>>> + GPU_IRQ_MASK_ERROR | >>>> + GPU_IRQ_PERFCNT_SAMPLE_COMPLETED | >>>> + GPU_IRQ_CLEAN_CACHES_COMPLETED); >>> >>> ...but if we do that, the next patch(es) will contain a partial revert of this >>> commit, putting back this to gpu_write(pfdev, GPU_INT_MASK, GPU_IRQ_MASK_ALL)... >> >> Why should we revert it? We're not processing the PWRTRANS interrupts >> in the interrupt handler, those should never have been enabled in the >> first place. The only reason we'd want to revert that change is if we >> decide to do have interrupt-based waits in the poweron/off >> implementation, which, as far as I'm aware, is not something we intend >> to do any time soon. >> > > You're right, yes. Okay, I'll push the new code soon. > > Cheers! >
Update: I was running some (rather fast) tests here because I ... felt like playing with it, basically :-)
So, I had an issue with MediaTek platforms being unable to cut power to the GPU or disable clocks aggressively... and after trying "this and that" I couldn't get it working (in runtime suspend).
Long story short - after implementing `panfrost_{job,mmu,gpu}_suspend_irq()` (only gpu irq, as you said, is a half solution), I can not only turn off clocks, but even turn off GPU power supplies entirely, bringing the power consumption of the GPU itself during *runtime* suspend to ... zero.
The result of this test makes me truly happy, even though complete powercut during runtime suspend may not be feasible for other reasons (takes ~200000ns on AVG, MIN ~160000ns, but the MAX is ~475000ns - and beware that I haven't run that for long, I'd suspect to get up to 1-1.5ms as max time, so that's a big no).
This means that I will take a day or two and I'll push both the "simple" fix for the Really-power-off and also some more commits to add the full irq sync.
Cheers! Angelo
>>> >>> I'm not sure that it's worth changing this like that, then changing it back right >>> after :-\ >>> >>> Anyway, if anyone else agrees with doing it and then partially revert, I have no >>> issues going with this one instead; what I care about ultimately is resolving the >>> regression ASAP :-) >>> >>> Cheers, >>> Angelo >>> >>>> /* >>>> * All in-flight jobs should have released their cycle >>>> @@ -425,11 +428,10 @@ void panfrost_gpu_power_on(struct panfrost_device *pfdev) >>>> void panfrost_gpu_power_off(struct panfrost_device *pfdev) >>>> { >>>> - u64 core_mask = panfrost_get_core_mask(pfdev); >>>> int ret; >>>> u32 val; >>>> - gpu_write(pfdev, SHADER_PWROFF_LO, pfdev->features.shader_present & >>>> core_mask); >>>> + gpu_write(pfdev, SHADER_PWROFF_LO, pfdev->features.shader_present); >>>> ret = readl_relaxed_poll_timeout(pfdev->iomem + SHADER_PWRTRANS_LO, >>>> val, !val, 1, 1000); >>>> if (ret) >>>> @@ -441,7 +443,7 @@ void panfrost_gpu_power_off(struct panfrost_device *pfdev) >>>> if (ret) >>>> dev_err(pfdev->dev, "tiler power transition timeout"); >>>> - gpu_write(pfdev, L2_PWROFF_LO, pfdev->features.l2_present & core_mask); >>>> + gpu_write(pfdev, L2_PWROFF_LO, pfdev->features.l2_present); >>>> ret = readl_poll_timeout(pfdev->iomem + L2_PWRTRANS_LO, >>>> val, !val, 0, 1000); >>>> if (ret) >>>> >>> >> > > >
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