linux-kernel - Re: [PATCH] drm/panfrost: Ignore core_mask for poweroff and sync interrupts

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Message-ID: <20231123145103.23b6eac9@collabora.com>
Date:   Thu, 23 Nov 2023 14:51:03 +0100
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     steven.price@....com, robh@...nel.org,
        maarten.lankhorst@...ux.intel.com, mripard@...nel.org,
        tzimmermann@...e.de, airlied@...il.com, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        krzysztof.kozlowski@...aro.org, kernel@...labora.com
Subject: Re: [PATCH] drm/panfrost: Ignore core_mask for poweroff and sync
 interrupts

On Thu, 23 Nov 2023 14:24:57 +0100
AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.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);
+       gpu_write(pfdev, GPU_INT_MASK,
+                 GPU_IRQ_MASK_ERROR |
+                 GPU_IRQ_PERFCNT_SAMPLE_COMPLETED |
+                 GPU_IRQ_CLEAN_CACHES_COMPLETED);
 
        /*
         * 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)