CMNT Re: [SRU][Q][PATCH 0/2] On Dell system, the internal OLED display drops to a visibly low FPS after suspend/resume

[Chia-Lin Kao (AceLan)]

On Tue, Apr 07, 2026 at 04:53:55PM +0300, Timo Aaltonen wrote:
> AceLan Kao kirjoitti 7.4.2026 klo 5.50:
> > From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>
> >
> > BugLink: https://bugs.launchpad.net/bugs/2144712
> >
> > [Impact]
> > On Dell systems (CID: 202511-38076), the internal OLED display drops to a
> > visibly lower refresh rate after suspend/resume. The state persists until a
> > cold reboot. Applications like glmark2 still report rendering at 120Hz but
> > the panel visually operates at a much lower frame rate.
> >
> > Steps to reproduce:
> > 1. Unplug all accessories
> > 2. Boot into OS
> > 3. Drag a window around the desktop and observe the FPS (smooth 120Hz)
> > 4. Suspend then resume
> > 5. Drag a window around the desktop — FPS is now visibly and permanently lower
> > Failure rate: 100% on affected hardware
> > Affected test case: com.canonical.certification::suspend/display_after_suspend
> >
> > Root cause: The i915 driver initializes Panel Replay (an OLED power-saving
> > feature) via DPCD negotiation during resume. On this specific panel, Panel
> > Replay causes the display to be locked at a degraded frame rate after resume.
> > The panel does not correctly handle Panel Replay activation in this
> > configuration, resulting in permanently reduced FPS until a cold reboot.
> >
> > [Fix]
> > Add a new quirk QUIRK_DISABLE_PANEL_REPLAY to the Intel i915 display driver
> > that prevents Panel Replay DPCD initialization for problematic panel setups.
> > Apply this quirk for Dell systems with device ID 0xb080, subsystem vendor
> > 0x1028, subsystem device 0x0db9, and sink OUI 0x00:0x22:0xb9.
> >
> > When the quirk is present, _panel_replay_init_dpcd() returns early before
> > reading Panel Replay capability from the panel's DPCD registers, effectively
> > disabling the Panel Replay feature for this hardware combination.
> >
> > The patch is currently under review in the Intel DRM/i915 mailing list:
> > https://patchwork.freedesktop.org/series/163265/
> >
> > Upstream issue tracker:
> > https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/7521
> >
> > In linux-next
> > 1de647abdfda9 drm/i915/psr: Fixes for Dell XPS DA14260 quirk
> > 45c77d4bf8d4d drm/i915/psr: Disable Panel Replay on Dell XPS 14 DA14260 as a quirk
> >
> > [Test Plan]
> > On a Dell system (CID: 202511-38076) with Intel integrated graphics:
> >
> > 1. Suspend and resume the system:
> >     $ sudo rtcwake -m mem -s 20
> > 2. After resume, drag a window around the desktop and observe the frame rate.
> >
> > Without the patch: The display FPS drops permanently after resume and stays
> > degraded until cold reboot.
> > With the patch: The display maintains normal 120Hz refresh rate after
> > suspend/resume.
> >
> > [Where problems could occur]
> > It may break Panel Replay functionality on Intel i915 display configurations.
> >
> > The quirk check is inserted early in _panel_replay_init_dpcd(), before any
> > DPCD reads occur. If the quirk match logic incorrectly identifies a panel
> > (e.g., due to incorrect OUI or PCI subsystem ID matching), Panel Replay will
> > be silently disabled on panels where it would otherwise work correctly. This
> > would cause affected systems to lose the power-saving benefits of Panel Replay
> > without any visible error — users would see slightly higher power consumption
> > on OLED panels.
> >
> > Additionally, if the quirk infrastructure itself has a bug (e.g., the
> > intel_has_dpcd_quirk() function returning unexpected values), it could either
> > fail to disable Panel Replay on affected hardware (regression still present)
> > or disable it too broadly on unaffected hardware.
> >
> > [Other Info]
> > The patch is under review in the Intel DRM mailing list (patchwork series
> > 163265) and has not yet landed in the mainline kernel.
> >
> > Jouni Högander (2):
> >    drm/i915/psr: Disable Panel Replay on Dell XPS 14 DA14260 as a quirk
> >    drm/i915/psr: Fixes for Dell XPS DA14260 quirk
> >
> >   drivers/gpu/drm/i915/display/intel_psr.c    |  8 +++++++
> >   drivers/gpu/drm/i915/display/intel_quirks.c | 25 ++++++++++++++++++---
> >   drivers/gpu/drm/i915/display/intel_quirks.h |  1 +
> >   3 files changed, 31 insertions(+), 3 deletions(-)
> >
>
> Note that you used the old bug for both of these, so the new bug (2145172)
> is redundant?
You are right, I forgot there is a new bug for the second patch.
Let me address the SRU submission on the new bug and mark it as
duplicated.

>
>
> --
> Timo Aaltonen
> Kernel Team
> Canonical Ltd.