linux-kernel - Re: [PATCH v6 05/11] drm/msm/a6xx: Implement preemption for a7xx targets

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Message-ID: <CAF6AEGviMOLoZKHf4DX9mEj84Y5Xx2hH4tvrkRVLsYyQz35Bwg@mail.gmail.com>
Date: Fri, 27 Sep 2024 09:29:58 -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>, 
	Jonathan Corbet <corbet@....net>, linux-arm-msm@...r.kernel.org, 
	dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
	Akhil P Oommen <quic_akhilpo@...cinc.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Sharat Masetty <smasetty@...eaurora.org>
Subject: Re: [PATCH v6 05/11] drm/msm/a6xx: Implement preemption for a7xx targets

On Thu, Sep 26, 2024 at 2:17 PM Antonino Maniscalco
<antomani103@...il.com> wrote:
>
> This patch implements preemption feature for A6xx targets, this allows
> the GPU to switch to a higher priority ringbuffer if one is ready. A6XX
> hardware as such supports multiple levels of preemption granularities,
> ranging from coarse grained(ringbuffer level) to a more fine grained
> such as draw-call level or a bin boundary level preemption. This patch
> enables the basic preemption level, with more fine grained preemption
> support to follow.
>
> Reviewed-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8650-QRD
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8550-QRD
> Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8450-HDK
> Signed-off-by: Sharat Masetty <smasetty@...eaurora.org>
> Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
> ---
>  drivers/gpu/drm/msm/Makefile              |   1 +
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c     | 283 +++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.h     | 168 +++++++++++++
>  drivers/gpu/drm/msm/adreno/a6xx_preempt.c | 377 ++++++++++++++++++++++++++++++
>  drivers/gpu/drm/msm/msm_ringbuffer.h      |   7 +
>  5 files changed, 825 insertions(+), 11 deletions(-)
>

[snip]

> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 6e065500b64d6d95599d89c33e6703c92f210047..355a3e210335d60a5bed0ee287912271c353402a 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c

[snip]

> @@ -784,6 +1015,16 @@ static int a6xx_ucode_load(struct msm_gpu *gpu)
>                 msm_gem_object_set_name(a6xx_gpu->shadow_bo, "shadow");
>         }
>
> +       a6xx_gpu->pwrup_reglist_ptr = msm_gem_kernel_new(gpu->dev, PAGE_SIZE,
> +                                                        MSM_BO_WC  | MSM_BO_MAP_PRIV,
> +                                                        gpu->aspace, &a6xx_gpu->pwrup_reglist_bo,
> +                                                        &a6xx_gpu->pwrup_reglist_iova);

Couldn't this also be MSM_BO_GPU_READONLY?  And same for the
preempt_postamble_ptr, I assume?

Also, it looks like we are only writing the smmu_info from the
kernel.. is there any way that could be split out into a RO buffer?

BR,
-R

> +
> +       if (IS_ERR(a6xx_gpu->pwrup_reglist_ptr))
> +               return PTR_ERR(a6xx_gpu->pwrup_reglist_ptr);
> +
> +       msm_gem_object_set_name(a6xx_gpu->pwrup_reglist_bo, "pwrup_reglist");
> +
>         return 0;
>  }
>