linux-kernel - [PATCH 0/3] drm/msm/dp: Improve DP AUX transfer vs. HPD interactions

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Date: Tue, 12 Mar 2024 17:13:15 -0700
From: Douglas Anderson <dianders@...omium.org>
To: Rob Clark <robdclark@...il.com>,
	Abhinav Kumar <quic_abhinavk@...cinc.com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Douglas Anderson <dianders@...omium.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Daniel Vetter <daniel@...ll.ch>,
	David Airlie <airlied@...il.com>,
	Guenter Roeck <groeck@...omium.org>,
	Kuogee Hsieh <quic_khsieh@...cinc.com>,
	Marijn Suijten <marijn.suijten@...ainline.org>,
	Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
	Sean Paul <sean@...rly.run>,
	Tanmay Shah <tanmay@...eaurora.org>,
	Vinod Polimera <quic_vpolimer@...cinc.com>,
	dri-devel@...ts.freedesktop.org,
	freedreno@...ts.freedesktop.org,
	linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 0/3] drm/msm/dp: Improve DP AUX transfer vs. HPD interactions

The main goal of this patch series is to avoid problems running
"fwupd" on Qualcomm devices. Right now several of the plugins used
with fwupd try talking over all DP AUX busses and this results in a
very long timeout on Qualcomm devices.

As part of fixing this, I noticed a case where the MSM DP code wasn't
respecing the timeout properly when asked to wait for HPD. I also
noticed that, now that we've implemented wait_hpd_asserted(), we no
longer need the long hardcoded timeout / special cse for eDP in the
AUX transfer function.

NOTE: I no longer have any hardware setup that uses this driver for
eDP so I've only tested the DP case. The eDP changes are
straightforward so hopefully there are no problems there.

Douglas Anderson (3):
  drm/msm/dp: Avoid a long timeout for AUX transfer if nothing connected
  drm/msm/dp: Account for the timeout in wait_hpd_asserted() callback
  drm/msm/dp: Delete the old 500 ms wait for eDP HPD in aux transfer

 drivers/gpu/drm/msm/dp/dp_aux.c     | 21 ++++++++-------------
 drivers/gpu/drm/msm/dp/dp_catalog.c | 17 ++++++++++++++---
 drivers/gpu/drm/msm/dp/dp_catalog.h |  4 +++-
 3 files changed, 25 insertions(+), 17 deletions(-)

-- 
2.44.0.278.ge034bb2e1d-goog