linux-kernel - Re: [PATCH v3 0/4] drm/dp: Make DP AUX bus usage easier; use it on ps8640

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Message-ID: <CAD=FV=W-gW_TMKKJA-5bCETp+KB4sAUDnMuGJMMTwAixb7Ho6w@mail.gmail.com>
Date:   Tue, 31 May 2022 14:03:56 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     dri-devel <dri-devel@...ts.freedesktop.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     Hsin-Yi Wang <hsinyi@...omium.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Philip Chen <philipchen@...omium.org>,
        Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
        Robert Foss <robert.foss@...aro.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Alex Deucher <alexander.deucher@....com>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Javier Martinez Canillas <javierm@...hat.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Lyude Paul <lyude@...hat.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Neil Armstrong <narmstrong@...libre.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/4] drm/dp: Make DP AUX bus usage easier; use it on ps8640

Hi,

On Tue, May 10, 2022 at 12:30 PM Douglas Anderson <dianders@...omium.org> wrote:
>
> This patch is v3 of the first 2 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 tries to incorporate all the feedback from v1. Hopefully
> things are less confusing and simpler this time around. The one thing that got
> slightly more confusing is that the done_probing() callback can't return
> -EPROBE_DEFER in most cases so we have to adjust drivers a little more.
>
> v3 takes Dmitry's advice on v2. This now introduces
> devm_drm_bridge_add() (in an extra patch), splits some fixups into
> their own patch, uses a new name for functions, and requires an
> explicit call to done_probing if you have no children.
>
> 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.
>
> NOTE: I don't have any ps8640 devices that _don't_ use the aux panel
> underneath them, so I'm relying on code inspection to make sure I
> didn't break those. If someone sees that I did something wrong for
> that case then please yell!
>
> [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 v3:
> - Adapt to v3 changes in aux bus.
> - Don't call done_probing() if there are no children; return -ENODEV.
> - Patch ("drm/bridge: Add devm_drm_bridge_add()") new for v3.
> - Patch ("drm/dp: Export symbol / kerneldoc fixes...") split for v3.
> - Split out EXPORT_SYMBOL and kerneldoc fixes to its own patch.
> - Use devm_drm_bridge_add() to simplify.
> - Used Dmitry's proposed name: of_dp_aux_populate_bus()
>
> Changes in v2:
> - Change to assume exactly one device.
> - Have a probe callback instead of an extra sub device.
> - Rewrote atop new method introduced by patch #1.
>
> Douglas Anderson (4):
>   drm/dp: Export symbol / kerneldoc fixes for DP AUX bus
>   drm/dp: Add callbacks to make using DP AUX bus properly easier
>   drm/bridge: Add devm_drm_bridge_add()
>   drm/bridge: parade-ps8640: Handle DP AUX more properly
>
>  drivers/gpu/drm/bridge/parade-ps8640.c   |  74 +++++---
>  drivers/gpu/drm/display/drm_dp_aux_bus.c | 211 +++++++++++++++--------
>  drivers/gpu/drm/drm_bridge.c             |  23 +++
>  include/drm/display/drm_dp_aux_bus.h     |  34 +++-
>  include/drm/drm_bridge.h                 |   1 +
>  5 files changed, 238 insertions(+), 105 deletions(-)

I'm hoping to get some review for this series. Anyone? Dmitry: I know
you looked at earlier versions of this series. I guess you're happy
enough with it now but don't feel enough ownership to give a full
Reviewed-by?

-Doug