linux-kernel - Re: [PATCH 2/2] drm/msm/dpu: try reserving the DSPP-less LM first

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <ff0c70f3-62aa-43f5-a437-62aae5b84e9c@packett.cool>
Date: Tue, 27 Jan 2026 07:59:34 -0300
From: Val Packett <val@...kett.cool>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Rob Clark <robin.clark@....qualcomm.com>,
 Abhinav Kumar <abhinav.kumar@...ux.dev>,
 Jessica Zhang <jesszhan0024@...il.com>, Sean Paul <sean@...rly.run>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, linux-arm-msm@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] drm/msm/dpu: try reserving the DSPP-less LM first


On 1/27/26 7:34 AM, Dmitry Baryshkov wrote:
> On Tue, Jan 27, 2026 at 06:43:32AM -0300, Val Packett wrote:
>> this has massively broken things on my x1e device (latitude-7455):
>> [..]
>> Reverted only this commit and it's back to normal, so I'm pretty sure it's
>> this.
> Interesting. Could you please capture the dri-state (only the last part,
> resource mapping) with the external monitor attached and with this
> commit reverted?

Just reverted:

crtc[106]: crtc-0 [..]
         mode: "2560x1600": 60 280710 2560 2608 2640 2720 1600 1603 1609 
1720 0x48 0x9
         lm[0]=0
         ctl[0]=0
         dspp[0]=0
         lm[1]=1
         ctl[1]=0
         dspp[1]=1
crtc[107]: crtc-1 [..]
         mode: "3840x2560": 60 631750 3840 3888 3920 4000 2560 2563 2573 
2633 0x48 0x9
         lm[0]=2
         ctl[0]=1
         lm[1]=3
         ctl[1]=1
resource mapping: pingpong=106 106 107 107 # # - - # # - - - mixer=106 
106 107 107 # # - - ctl=106 107 # # # # - - dspp=# # # # - - - - dsc=# # 
# # - - - - cdm=# sspp=# # # # - - - - # # # # # # - - cwb=- - - -

> Also, could you please run another check:
>   - revert this commit
>   - comment out LM_2, LM_3 in the catalog
>   - try the resulting kernel with the external monitor

Commented out:

crtc[106]: crtc-0 [..]
         mode: "2560x1600": 60 280710 2560 2608 2640 2720 1600 1603 1609 
1720 0x48 0x9
         lm[0]=0
         ctl[0]=0
         dspp[0]=0
         lm[1]=1
         ctl[1]=0
         dspp[1]=1
crtc[107]: crtc-1 [..]
         mode: "3840x2560": 60 631750 3840 3888 3920 4000 2560 2563 2573 
2633 0x48 0x9
         lm[0]=4
         ctl[0]=1
         lm[1]=5
         ctl[1]=1
resource mapping:
         pingpong=106 106 # # 107 107 - - # # - - -
         mixer=106 106 - - 107 107 - -
         ctl=106 107 # # # # - -
         dspp=# # # # - - - -
         dsc=# # # # - - - -
         cdm=#
         sspp=# # # # - - - - # # # # # # - -
         cwb=- - - -

Not sure why the dspp= line in resource mapping doesn't show any numbers 
when a crtc has dspp[0]= and dspp[1]= o.0

But with LM 4+5, gamma control doesn't affect the external monitor.


~val