drm/i915/psr: clear the Panel Replay error status register

psr_get_status_and_error_status() selects the DPCD offset to read the error
status from based on whether Panel Replay is enabled:

	offset = intel_dp->psr.panel_replay_enabled ?
		 DP_PANEL_REPLAY_ERROR_STATUS : DP_PSR_ERROR_STATUS;

but intel_psr_short_pulse() acknowledges it unconditionally to the PSR
register. Under Panel Replay the error is therefore read from
DP_PANEL_REPLAY_ERROR_STATUS (0x2020) and the acknowledgment written to
DP_PSR_ERROR_STATUS (0x2006). DP_PANEL_REPLAY_ERROR_STATUS is never written
anywhere in the tree; it appears only in the read above and in its own

The sink's Panel Replay error latch can consequently never be cleared. Once
it latches, every subsequent short pulse re-reads the same errors, so PSR
is disabled with sink_not_reliable set permanently, and until a short pulse
arrives the driver keeps Panel Replay enabled while the sink is reporting
errors it cannot see.

Observed on a Dell XPS 16 DA16260 (Panther Lake, Arc B390, display version
30.00) with the eDP Panel Replay quirk from commit cb8d155b0806
("drm/i915/psr: Disable Panel Replay on Dell XPS 16 DA16260 as a quirk")
removed locally so the feature could be exercised.
The sink reports a persistently latched error:

	Sink PANEL-REPLAY status: 0x2 [active, display from RFB]
	Sink PANEL-REPLAY error status: 0x1:
		PANEL-REPLAY Link CRC error

which survives across reads indefinitely, while dmesg stays silent and
Panel Replay Selective Update remains enabled.

Use the same conditional offset when clearing. psr->panel_replay_enabled
cannot be used at that point because intel_psr_disable_locked() clears it
earlier in the same function whenever an error was detected, which is
exactly the case that needs the Panel Replay offset, so save it beforehand.

v2: use a copy of panel_replay_enabled taken before
    intel_psr_disable_locked() clears it. In v1 the condition was evaluated
    after the disable, so it selected DP_PSR_ERROR_STATUS in the error path
    and the patch was a no-op there. Caught by Sashiko AI review.

Signed-off-by: Jake Steinman <j@metarealtyinc.ca>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20260901205956.130779-1-j@metarealtyinc.ca
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
[Rodrigo: adjusted commit message based on checkpatch]

0 files changed, 0 insertions, 0 deletions