linux-kernel - Re: [PATCH] drm/bridge: adv7511: Do not merge adv7511_mode_set() with atomic

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: <91d8a288-1f2d-469c-a596-6265893584ae@bp.renesas.com>
Date: Mon, 26 May 2025 11:58:37 +0200
From: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
To: Maxime Ripard <mripard@...nel.org>
Cc: tomm.merciai@...il.com, linux-renesas-soc@...r.kernel.org,
 biju.das.jz@...renesas.com, Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>,
 Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>,
 Douglas Anderson <dianders@...omium.org>, Adam Ford <aford173@...il.com>,
 Jesse Van Gavere <jesseevg@...il.com>, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/bridge: adv7511: Do not merge adv7511_mode_set() with
 atomic_enable()

Hi Maxime,
Thanks for your comment.

On 26/05/25 11:26, Maxime Ripard wrote:
> Hi,
> 
> On Mon, May 26, 2025 at 10:54:52AM +0200, Tommaso Merciai wrote:
>> After adv7511_mode_set() was merged into .atomic_enable(), only the
>> native resolution is working when using modetest.
>>
>> This is caused by incorrect timings: adv7511_mode_set() must not be
>> merged into .atomic_enable().
>>
>> Move adv7511_mode_set() back to the .mode_set() callback in
>> drm_bridge_funcs to restore correct behavior.
>>
>> Fixes: 0a9e2f0a6466 ("drm/bridge: adv7511: switch to the HDMI connector helpers")
>> Reported-by: Biju Das <biju.das.jz@...renesas.com>
>> Closes: https://lore.kernel.org/all/aDB8bD6cF7qiSpKd@tom-desktop/
>> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@...renesas.com>
> 
> Explaining why, both in the commit log and the comments, would be nice.
> Because I can't think of any good reason it just can't work for that
> bridge.

Sorry, let me clarify and share with you some details:

adv7511_mode_set:
  - Is setting up timings registers for the DSI2HDMI bridge in our case
    we are using ADV7535 bridge.

rzg2l_mipi_dsi_atomic_enable:
  - Is setting up the vclock for the DSI ip

Testing new/old implementation a bit we found the following:

root@...rc-rzg3e:~# modetest -M rzg2l-du -d -s HDMI-A-1:800x600-56.25@...4
setting mode 800x600-56.25Hz on connectors HDMI-A-1, crtc 62
[   49.273134] adv7511_mode_set_old: drm_mode_vrefresh(mode) = 56
[   49.281006] rzg2l_mipi_dsi_atomic_enable: mode->clock: 36000

root@...rc-rzg3e:~# modetest -M rzg2l-du -d -s HDMI-A-1:800x600-56.25@...4
setting mode 800x600-56.25Hz on connectors HDMI-A-1, crtc 62
[   74.076881] rzg2l_mipi_dsi_atomic_enable: mode->clock: 36000
[   74.092130] adv7511_mode_set: drm_mode_vrefresh(adj_mode) = 56

Same result but different timing (in function call perspective):

  - old: adv7511_mode_set() is call before rzg2l_mipi_dsi_atomic_enable()
  - new: adv7511_mode_set() is call after rzg2l_mipi_dsi_atomic_enable()

What do you think? Thanks in advance.

Thanks & Regards,
Tommaso

> 
> Maxime