drm/i915/dp: Don't switch the LTTPR mode on an active link

Browse source

commit 509580fad7 upstream.

Switching to transparent mode leads to a loss of link synchronization,
so prevent doing this on an active link. This happened at least on an
Intel N100 system / DELL UD22 dock, the LTTPR residing either on the
host or the dock. To fix the issue, keep the current mode on an active
link, adjusting the LTTPR count accordingly (resetting it to 0 in
transparent mode).

v2: Adjust code comment during link training about reiniting the LTTPRs.
   (Ville)

Fixes: 7b2a4ab8b0 ("drm/i915: Switch to LTTPR transparent mode link training")
Reported-and-tested-by: Gareth Yu <gareth.yu@intel.com>
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10902
Cc: <stable@vger.kernel.org> # v5.15+
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708190029.271247-3-imre.deak@intel.com
(cherry picked from commit 211ad49cf8)
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Imre Deak 2024-07-08 22:00:25 +03:00 • committed by Greg Kroah-Hartman

parent a90e900f71

commit 12880cc086

1 changed files with 48 additions and 7 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

55

drivers/gpu/drm/i915/display/intel_dp_link_training.c

View file