linux-kernel - Re: [PATCH] drm/msm: Fix a6xx GMU shutdown sequence

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Message-ID: <20200123191636.GY89495@google.com>
Date:   Thu, 23 Jan 2020 11:16:36 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Jordan Crouse <jcrouse@...eaurora.org>
Cc:     linux-arm-msm@...r.kernel.org, Sean Paul <sean@...rly.run>,
        Sharat Masetty <smasetty@...eaurora.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Douglas Anderson <dianders@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        freedreno@...ts.freedesktop.org, Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH] drm/msm: Fix a6xx GMU shutdown sequence

Hi Jordan,

On Thu, Jan 23, 2020 at 09:42:36AM -0700, Jordan Crouse wrote:
> Commit e812744c5f95 ("drm: msm: a6xx: Add support for A618") missed
> updating the VBIF flush in a6xx_gmu_shutdown and instead
> inserted the new sequence into a6xx_pm_suspend along with a redundant
> GMU idle.
> 
> Move a6xx_bus_clear_pending_transactions to a6xx_gmu.c and use it in
> the appropriate place in the shutdown routine and remove the redundant
> idle call.
> 
> Signed-off-by: Jordan Crouse <jcrouse@...eaurora.org>
> ---
> 
>  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 36 +++++++++++++++++++++++++----
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 43 -----------------------------------
>  2 files changed, 31 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index 983afea..f371227 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
>
> ...
>
>  /* Gracefully try to shut down the GMU and by extension the GPU */
>  static void a6xx_gmu_shutdown(struct a6xx_gmu *gmu)
>  {
> @@ -819,11 +849,7 @@ static void a6xx_gmu_shutdown(struct a6xx_gmu *gmu)
>  			return;
>  		}
>  
> -		/* Clear the VBIF pipe before shutting down */
> -		gpu_write(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL0, 0xf);
> -		spin_until((gpu_read(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL1) & 0xf)
> -			== 0xf);
> -		gpu_write(gpu, REG_A6XX_VBIF_XIN_HALT_CTRL0, 0);
> +		a6xx_bus_clear_pending_transactions(adreno_gpu);

With this the variable 'gpu' isn't used anymore in a6xx_gmu_shutdown(),
please remove it.