linux-kernel - Re: [PATCH 4/7] drm/msm/a5xx: Reset VBIF before PC only on A510 and A530

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Date:   Mon, 28 Sep 2020 10:25:56 -0600
From:   Jordan Crouse <jcrouse@...eaurora.org>
To:     kholk11@...il.com
Cc:     robdclark@...il.com, sean@...rly.run, airlied@...ux.ie,
        daniel@...ll.ch, konradybcio@...il.com, marijns95@...il.com,
        martin.botka1@...il.com, linux-arm-msm@...r.kernel.org,
        freedreno@...ts.freedesktop.org, phone-devel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] drm/msm/a5xx: Reset VBIF before PC only on A510 and
 A530

On Sat, Sep 26, 2020 at 02:51:43PM +0200, kholk11@...il.com wrote:
> From: AngeloGioacchino Del Regno <kholk11@...il.com>
> 
> Resetting the VBIF before power collapse is done to avoid getting
> bogus FIFO entries during the suspend sequence or subsequent resume,
> but this is doable only on Adreno 510 and Adreno 530, as the other
> units will tendentially lock up.
> Especially on Adreno 508, the GPU will show lockups and very bad
> slownesses after processing the first frame.
> 
> Avoiding to execute the RBBM SW Reset before suspend will stop the
> lockup issue from happening on at least Adreno 508/509/512.

Reviewed-by: Jordan Crouse <jcrouse@...eaurora.org>

> Signed-off-by: AngeloGioacchino Del Regno <kholk11@...il.com>
> ---
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index 9bcbf6cd5a28..00df5de3c8e3 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -1306,10 +1306,12 @@ static int a5xx_pm_suspend(struct msm_gpu *gpu)
>  
>  	/*
>  	 * Reset the VBIF before power collapse to avoid issue with FIFO
> -	 * entries
> +	 * entries on Adreno A510 and A530 (the others will tend to lock up)
>  	 */
> -	gpu_write(gpu, REG_A5XX_RBBM_BLOCK_SW_RESET_CMD, 0x003C0000);
> -	gpu_write(gpu, REG_A5XX_RBBM_BLOCK_SW_RESET_CMD, 0x00000000);
> +	if (adreno_is_a510(adreno_gpu) || adreno_is_a530(adreno_gpu)) {
> +		gpu_write(gpu, REG_A5XX_RBBM_BLOCK_SW_RESET_CMD, 0x003C0000);
> +		gpu_write(gpu, REG_A5XX_RBBM_BLOCK_SW_RESET_CMD, 0x00000000);
> +	}
>  
>  	return msm_gpu_pm_suspend(gpu);
>  }
> -- 
> 2.28.0
> 

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