linux-kernel - Re: [PATCH v16 09/10] drm/msm/dpu: support plane splitting in quad-pipe case

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Message-ID: <z75wnahrp7lrl5yhfdysr3np3qrs6xti2i4otkng4ex3blfgrx@xyiucge3xykb>
Date: Thu, 18 Dec 2025 14:44:43 +0200
From: Abel Vesa <abel.vesa@....qualcomm.com>
To: Jun Nie <jun.nie@...aro.org>
Cc: Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Dmitry Baryshkov <lumag@...nel.org>, Sean Paul <sean@...rly.run>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Rob Clark <robin.clark@....qualcomm.com>,
        Jessica Zhang <jessica.zhang@....qualcomm.com>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v16 09/10] drm/msm/dpu: support plane splitting in
 quad-pipe case

On 25-09-18 21:29:01, Jun Nie wrote:
> The content of every half of screen is sent out via one interface in
> dual-DSI case. The content for every interface is blended by a LM
> pair in quad-pipe case, thus a LM pair should not blend any content
> that cross the half of screen in this case. Clip plane into pipes per
> left and right half screen ROI if topology is quad pipe case.
> 
> The clipped rectangle on every half of screen is futher handled by two
> pipes if its width exceeds a limit for a single pipe.
> 
> Signed-off-by: Jun Nie <jun.nie@...aro.org>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Reviewed-by: Jessica Zhang <jessica.zhang@....qualcomm.com>

At least on Hamoa based devices (CRD and xps13) I have been seeing on every
boot the following:

arm-smmu 15000000.iommu: Unhandled context fault: fsr=0x402, iova=0x00000000, fsynr=0x3d0023, cbfrsynra=0x1c00, cb=13
arm-smmu 15000000.iommu: FSR    = 00000402 [Format=2 TF], SID=0x1c00
arm-smmu 15000000.iommu: FSYNR0 = 003d0023 [S1CBNDX=61 PNU PLVL=3]

Also there are some artifacts on eDP (no DP connected) on the xps13 with 2880x1800
(LGD 134WT1) panel. Not on CRD though.

Reverting this commit fixes it:
5978864e34b6 ("drm/msm/dpu: support plane splitting in quad-pipe case")

Discussing this off-list with Dmitry and Konrad, the conclusion was that
both this plus following commit should be reverted for the time being:

d7ec9366b15c ("drm/msm/dpu: Enable quad-pipe for DSC and dual-DSI case")