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

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Message-ID: <aXDt6v_iO4EFCqyw@hovoldconsulting.com>
Date: Wed, 21 Jan 2026 16:16:58 +0100
From: Johan Hovold <johan@...nel.org>
To: 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 Wed, Jan 14, 2026 at 09:56:12AM +0100, Johan Hovold wrote:
> On Sun, Dec 21, 2025 at 05:45:52PM +0100, 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.
> > 
> > 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>
> > ---
> 
> This one does not seem to have been applied yet despite fixing a
> critical regression in 6.19-rc1. I guess I could have highlighted that
> further by also including:
> 
> Fixes: 188db3d7fe66 ("drm/msm/a6xx: Rebase GMU register offsets")
> 
> I realise some delays are expected around Christmas, but can you please
> try to get this fix to Linus now that everyone should be back again?

I haven't received any reply so was going to send another reminder, but
I noticed now that this patch was merged to the msm-next branch last
week.

Since it fixes a regression in 6.19-rc1 it needs to go to Linus this
cycle and I would have assumed it should have be merged to msm-fixes.

(MSM) DRM works in mysterious ways, so can someone please confirm that
this regression fix is heading into mainline for 6.19-final?

Johan