linux-kernel - Re: [PATCH v2 9/9] drm/msm/A6xx: Enable preemption for A750

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Message-ID: <CAF6AEGui3bFqTqwhSCcx38=WzbaHKmnttjXiff-=GT0HHQyapw@mail.gmail.com>
Date: Fri, 30 Aug 2024 11:23:58 -0700
From: Rob Clark <robdclark@...il.com>
To: Antonino Maniscalco <antomani103@...il.com>
Cc: Sean Paul <sean@...rly.run>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Daniel Vetter <daniel@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v2 9/9] drm/msm/A6xx: Enable preemption for A750

On Fri, Aug 30, 2024 at 8:33 AM Antonino Maniscalco
<antomani103@...il.com> wrote:
>
> Initialize with 4 rings to enable preemption.
>
> For now only on A750 as other targets require testing.
>
> Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8650-QRD
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index a2853309288b..ea518209c03d 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -2609,7 +2609,9 @@ struct msm_gpu *a6xx_gpu_init(struct drm_device *dev)
>                 return ERR_PTR(ret);
>         }
>
> -       if (is_a7xx)
> +       if (adreno_is_a750(adreno_gpu))
> +               ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_a7xx, 4);

perhaps it would be useful (to enable others to more easily test), to
allow this to be overridden with a modparam.. something like

       if ((enable_preemption == 1) || (enable_preemption == -1 &&
(config->info->quirks & ADRENO_QUIRK_PREEMPTION))

That would allow overriding enable_preemption to 1 or 0 on cmdline to
force enable/disable preemption.

That plus some instructions about how to test preemption (ie. what
deqp tests to run, or similar) would make it easier to "crowd source"
the testing (assuming you don't have every a7xx device there is)

BR,
-R

> +       else if (is_a7xx)
>                 ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_a7xx, 1);
>         else if (adreno_has_gmu_wrapper(adreno_gpu))
>                 ret = adreno_gpu_init(dev, pdev, adreno_gpu, &funcs_gmuwrapper, 1);
>
> --
> 2.46.0
>