linux-kernel - Re: [PATCH v4 3/5] drm/msm/a6xx: Vote for cx gdsc from gpu driver

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Message-ID: <CAPDyKFqFrf5qVpsQs-cwYnazBBjG-QkKxFL1szNmz+x3hq27gg@mail.gmail.com>
Date:   Thu, 22 Dec 2022 17:09:51 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc:     freedreno <freedreno@...ts.freedesktop.org>,
        dri-devel@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Rob Clark <robdclark@...il.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Sean Paul <sean@...rly.run>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/5] drm/msm/a6xx: Vote for cx gdsc from gpu driver

On Wed, 21 Dec 2022 at 18:14, Akhil P Oommen <quic_akhilpo@...cinc.com> wrote:
>
> When a device has multiple power domains, dev->power_domain is left
> empty during probe. That didn't cause any issue so far because we are
> freeloading on smmu driver's vote on cx gdsc. Instead of that, create
> a device_link between cx genpd device and gmu device to keep a vote from
> gpu driver.
>
> Before this patch:
> localhost ~ # cat /sys/kernel/debug/pm_genpd/pm_genpd_summary
> gx_gdsc         on              0
>     /devices/genpd:1:3d6a000.gmu                active          0
> cx_gdsc         on              0
>     /devices/platform/soc@...da0000.iommu       active          0
>
> After this patch:
> localhost ~ # cat /sys/kernel/debug/pm_genpd/pm_genpd_summary
> gx_gdsc         on              0
>     /devices/genpd:1:3d6a000.gmu                active          0
> cx_gdsc         on              0
>     /devices/platform/soc@...da0000.iommu       active          0
>     /devices/genpd:0:3d6a000.gmu                active          0
>
> Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Kind regards
Uffe

> ---
>
> (no changes since v1)
>
>  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 31 +++++++++++++++++++++++++++----
>  drivers/gpu/drm/msm/adreno/a6xx_gmu.h |  1 +
>  2 files changed, 28 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index 6484b97c5344..1580d0090f35 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -1479,6 +1479,12 @@ void a6xx_gmu_remove(struct a6xx_gpu *a6xx_gpu)
>
>         pm_runtime_force_suspend(gmu->dev);
>
> +       /*
> +        * Since cxpd is a virt device, the devlink with gmu-dev will be removed
> +        * automatically when we do detach
> +        */
> +       dev_pm_domain_detach(gmu->cxpd, false);
> +
>         if (!IS_ERR_OR_NULL(gmu->gxpd)) {
>                 pm_runtime_disable(gmu->gxpd);
>                 dev_pm_domain_detach(gmu->gxpd, false);
> @@ -1605,8 +1611,10 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
>
>         if (adreno_is_a650_family(adreno_gpu)) {
>                 gmu->rscc = a6xx_gmu_get_mmio(pdev, "rscc");
> -               if (IS_ERR(gmu->rscc))
> +               if (IS_ERR(gmu->rscc)) {
> +                       ret = -ENODEV;
>                         goto err_mmio;
> +               }
>         } else {
>                 gmu->rscc = gmu->mmio + 0x23000;
>         }
> @@ -1615,8 +1623,22 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
>         gmu->hfi_irq = a6xx_gmu_get_irq(gmu, pdev, "hfi", a6xx_hfi_irq);
>         gmu->gmu_irq = a6xx_gmu_get_irq(gmu, pdev, "gmu", a6xx_gmu_irq);
>
> -       if (gmu->hfi_irq < 0 || gmu->gmu_irq < 0)
> +       if (gmu->hfi_irq < 0 || gmu->gmu_irq < 0) {
> +               ret = -ENODEV;
> +               goto err_mmio;
> +       }
> +
> +       gmu->cxpd = dev_pm_domain_attach_by_name(gmu->dev, "cx");
> +       if (IS_ERR(gmu->cxpd)) {
> +               ret = PTR_ERR(gmu->cxpd);
>                 goto err_mmio;
> +       }
> +
> +       if (!device_link_add(gmu->dev, gmu->cxpd,
> +                                       DL_FLAG_PM_RUNTIME)) {
> +               ret = -ENODEV;
> +               goto detach_cxpd;
> +       }
>
>         /*
>          * Get a link to the GX power domain to reset the GPU in case of GMU
> @@ -1634,6 +1656,9 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
>
>         return 0;
>
> +detach_cxpd:
> +       dev_pm_domain_detach(gmu->cxpd, false);
> +
>  err_mmio:
>         iounmap(gmu->mmio);
>         if (platform_get_resource_byname(pdev, IORESOURCE_MEM, "rscc"))
> @@ -1641,8 +1666,6 @@ int a6xx_gmu_init(struct a6xx_gpu *a6xx_gpu, struct device_node *node)
>         free_irq(gmu->gmu_irq, gmu);
>         free_irq(gmu->hfi_irq, gmu);
>
> -       ret = -ENODEV;
> -
>  err_memory:
>         a6xx_gmu_memory_free(gmu);
>  err_put_device:
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
> index e034935b3986..5a42dd4dd31f 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
> @@ -56,6 +56,7 @@ struct a6xx_gmu {
>         int gmu_irq;
>
>         struct device *gxpd;
> +       struct device *cxpd;
>
>         int idle_level;
>
> --
> 2.7.4
>