Re: [PATCH 0/2] drm/client: Keep larger modes in connector->modes on fbdev hotplug

[Hugo Sales]

On Fri, Oct 16, 2026 at 03:28:39PM +0300, Ville Syrjälä wrote:
> On Thu, Oct 15, 2026 at 10:25:43PM +0100, Hugo Sales wrote:
> > On an ASUS ROG Flow X13 with a 3840x2400 eDP panel, booted with
> > video=eDP-1:1920x1200@60, an HDMI hotplug makes fbdev reprobe every
> > connector with its 1920x1200 framebuffer as the limit. connector->modes
> > loses the panel's 3840x2400 mode, and after suspend/resume amdgpu drives
> > the panel with the 1920x1200 timing. The image ends up squeezed into the
> > top-left corner. Details are in
> > https://gitlab.freedesktop.org/drm/amd/-/issues/5983
>
> Sounds like an amdgpu bug.

Agreed, the resume bug is in amdgpu. It looks up the eDP native mode in
connector->modes, which fbdev's hotplug probe can trim. This series
fixes it there:
https://lore.kernel.org/r/20261014223041.171317-1-hugo@xxxxxxx

I sent this one for the shared list itself because after a hotplug,
connector->modes depends on fbdev's framebuffer size, while initial
setup, drm_log and GETCONNECTOR probe with the device's limits. Until
something reprobes, the sysfs modes file and any driver that reads the
list see the trimmed version

amdgpu isn't the only driver that reads it. stm/lvds and
shmob_drm_encoder_mode_fixup() take the first entry of connector->modes
as the panel mode, so they may hit the same thing with a video= mode
smaller than the panel. I haven't tested those, because I don't have
the hardware. Fixing it in the core covers them without each driver
keeping its own copy of the native mode

Hugo