linux-kernel - Re: [PATCH 5/7] drm/msm/a5xx: Fix VPC protect value in gpu

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Message-ID: <20200928161546.GB29832@jcrouse1-lnx.qualcomm.com>
Date:   Mon, 28 Sep 2020 10:15:46 -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 5/7] drm/msm/a5xx: Fix VPC protect value in gpu_write()

On Sat, Sep 26, 2020 at 02:51:44PM +0200, kholk11@...il.com wrote:
> From: Konrad Dybcio <konradybcio@...il.com>
> 
> The upstream API for some reason uses logbase2 instead of
> just passing the argument as-is, whereas downstream CAF
> kernel does the latter.
> 
> Hence, a mistake has been made when porting:
> 4 is the value that's supposed to be passed, but
> log2(4) = 2. Changing the value to 16 (= 2^4) fixes
> the issue.

FWIW I think downstream is wrong. Its a lot more intuitive to pass the number of
registers that should be protected than to force a human to do math.

Jordan

> Signed-off-by: Konrad Dybcio <konradybcio@...il.com>
> Signed-off-by: AngeloGioacchino Del Regno <kholk11@...il.com>
> ---
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index 00df5de3c8e3..b2670af638a3 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -789,7 +789,7 @@ static int a5xx_hw_init(struct msm_gpu *gpu)
>  
>  	/* VPC */
>  	gpu_write(gpu, REG_A5XX_CP_PROTECT(14), ADRENO_PROTECT_RW(0xE68, 8));
> -	gpu_write(gpu, REG_A5XX_CP_PROTECT(15), ADRENO_PROTECT_RW(0xE70, 4));
> +	gpu_write(gpu, REG_A5XX_CP_PROTECT(15), ADRENO_PROTECT_RW(0xE70, 16));
>  
>  	/* UCHE */
>  	gpu_write(gpu, REG_A5XX_CP_PROTECT(16), ADRENO_PROTECT_RW(0xE80, 16));
> -- 
> 2.28.0
> 

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