linux-kernel - [PATCH v4 0/4] drm/dp: Introduce wait_hpd

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Message-Id: <20220614215418.910948-1-dianders@chromium.org>
Date:   Tue, 14 Jun 2022 14:54:14 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     dri-devel@...ts.freedesktop.org
Cc:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Robert Foss <robert.foss@...aro.org>,
        Philip Chen <philipchen@...omium.org>,
        Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Douglas Anderson <dianders@...omium.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Imre Deak <imre.deak@...el.com>,
        Jani Nikula <jani.nikula@...el.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Lyude Paul <lyude@...hat.com>,
        Maxime Ripard <maxime@...no.tech>,
        Neil Armstrong <narmstrong@...libre.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>, linux-kernel@...r.kernel.org
Subject: [PATCH v4 0/4] drm/dp: Introduce wait_hpd_asserted() for the DP AUX bus

This is the 2nd four patches from my RFC series ("drm/dp: Improvements
for DP AUX channel") [1]. I've broken the series in two so we can make
progress on the two halves separately.

v2 of this series changes to add wait_hpd_asserted() instead of
is_hpd_asserted(). This allows us to move the extra delay needed for
ps8640 into the ps8640 driver itself.

The idea for this series came up during the review process of
Sankeerth's series trying to add eDP for Qualcomm SoCs [2].

This _doesn't_ attempt to fix the Analogix driver. If this works out,
ideally someone can post a patch up to do that.

[1] https://lore.kernel.org/r/20220409023628.2104952-1-dianders@chromium.org/
[2] https://lore.kernel.org/r/1648656179-10347-2-git-send-email-quic_sbillaka@quicinc.com/

Changes in v4:
- Add comment that caller powered up the panel.
- Comments now explain that we may wait longer due to debouncing.
- Mention in commit message debouncing vs. powering on timing.
- Rebased to handle the fact that the stuct moved files.
- Reorganized logic as per Dmitry's suggestion.

Changes in v3:
- Don't check "hpd_asserted" boolean when unset.
- Handle errors from gpiod_get_value_cansleep() properly.

Changes in v2:
- Change is_hpd_asserted() to wait_hpd_asserted()

Douglas Anderson (4):
  drm/dp: Add wait_hpd_asserted() callback to struct drm_dp_aux
  drm/panel-edp: Take advantage of wait_hpd_asserted() in struct
    drm_dp_aux
  drm/panel: atna33xc20: Take advantage of wait_hpd_asserted() in struct
    drm_dp_aux
  drm/bridge: parade-ps8640: Provide wait_hpd_asserted() in struct
    drm_dp_aux

 drivers/gpu/drm/bridge/parade-ps8640.c        | 39 +++++++++-----
 drivers/gpu/drm/panel/panel-edp.c             | 33 ++++++++----
 .../gpu/drm/panel/panel-samsung-atna33xc20.c  | 51 ++++++++++++++-----
 include/drm/display/drm_dp_helper.h           | 30 +++++++++++
 4 files changed, 117 insertions(+), 36 deletions(-)

-- 
2.36.1.476.g0c4daa206d-goog