linux-kernel - Re: [PATCH] drm/msm/a6xx: fix bogus hwcg register updates

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Message-ID: <e4748c15-935e-4dd0-a49f-a68921074922@oss.qualcomm.com>
Date: Mon, 22 Dec 2025 09:51:59 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Johan Hovold <johan@...nel.org>, Rob Clark
 <robin.clark@....qualcomm.com>,
        Sean Paul <sean@...rly.run>
Cc: Konrad Dybcio <konradybcio@...nel.org>,
        Akhil P Oommen <akhilpo@....qualcomm.com>,
        Dmitry Baryshkov <lumag@...nel.org>,
        Abhinav Kumar
 <abhinav.kumar@...ux.dev>,
        Jessica Zhang <jesszhan0024@...il.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Bjorn Andersson <andersson@...nel.org>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH] drm/msm/a6xx: fix bogus hwcg register updates

On 12/21/25 5:45 PM, Johan Hovold wrote:
> The hw clock gating register sequence consists of register value pairs
> that are written to the GPU during initialisation.
> 
> The a690 hwcg sequence has two GMU registers in it that used to amount
> to random writes in the GPU mapping, but since commit 188db3d7fe66
> ("drm/msm/a6xx: Rebase GMU register offsets") they trigger a fault as
> the updated offsets now lie outside the mapping. This in turn breaks
> boot of machines like the Lenovo ThinkPad X13s.
> 
> Note that the updates of these GMU registers is already taken care of
> properly since commit 40c297eb245b ("drm/msm/a6xx: Set GMU CGC
> properties on a6xx too"), but for some reason these two entries were
> left in the table.

I am squinting *very* hard and I can not recall why I only removed one
of these entries.

> 
> Fixes: 5e7665b5e484 ("drm/msm/adreno: Add Adreno A690 support")
> Cc: stable@...r.kernel.org	# 6.5
> Cc: Bjorn Andersson <andersson@...nel.org>
> Cc: Konrad Dybcio <konradybcio@...nel.org>
> Signed-off-by: Johan Hovold <johan@...nel.org>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_catalog.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
> index 29107b362346..4c2f739ee9b7 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
> @@ -501,8 +501,6 @@ static const struct adreno_reglist a690_hwcg[] = {
>  	{REG_A6XX_RBBM_CLOCK_CNTL_GMU_GX, 0x00000222},
>  	{REG_A6XX_RBBM_CLOCK_DELAY_GMU_GX, 0x00000111},
>  	{REG_A6XX_RBBM_CLOCK_HYST_GMU_GX, 0x00000555},
> -	{REG_A6XX_GPU_GMU_AO_GMU_CGC_DELAY_CNTL, 0x10111},
> -	{REG_A6XX_GPU_GMU_AO_GMU_CGC_HYST_CNTL, 0x5555},

Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>

Konrad