linux-kernel - Re: [PATCH 00/20] drm/bridge: tc358775: proper bridge bringup and code cleanup

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Message-Id: <D1QCW5G2I7E0.2MM683BWHR5N1@kernel.org>
Date: Mon, 03 Jun 2024 13:47:20 +0200
From: "Michael Walle" <mwalle@...nel.org>
To: "Michael Walle" <mwalle@...nel.org>, "Andrzej Hajda"
 <andrzej.hajda@...el.com>, "Neil Armstrong" <neil.armstrong@...aro.org>,
 "Robert Foss" <rfoss@...nel.org>, "Laurent Pinchart"
 <Laurent.pinchart@...asonboard.com>, "Jonas Karlman" <jonas@...boo.se>,
 "Jernej Skrabec" <jernej.skrabec@...il.com>, "Maarten Lankhorst"
 <maarten.lankhorst@...ux.intel.com>, "Maxime Ripard" <mripard@...nel.org>,
 "Thomas Zimmermann" <tzimmermann@...e.de>, "David Airlie"
 <airlied@...il.com>, "Daniel Vetter" <daniel@...ll.ch>, "Chun-Kuang Hu"
 <chunkuang.hu@...nel.org>, "Philipp Zabel" <p.zabel@...gutronix.de>,
 "Matthias Brugger" <matthias.bgg@...il.com>, "AngeloGioacchino Del Regno"
 <angelogioacchino.delregno@...labora.com>, "Sam Ravnborg"
 <sam@...nborg.org>, "Vinay Simha BN" <simhavcs@...il.com>, "Tony Lindgren"
 <tony@...mide.com>
Cc: "Daniel Semkowicz" <dse@...umatec.com>,
 <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
 <linux-mediatek@...ts.infradead.org>,
 <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 00/20] drm/bridge: tc358775: proper bridge bringup and
 code cleanup

On Mon May 6, 2024 at 3:34 PM CEST, Michael Walle wrote:
> This patchset fixes the bridge initialization according to the
> datasheet. Not sure how that even worked before. Maybe because the
> initialization was done prior to linux (?).
>
> The bridge has some peculiarities:
>  (1) The reset has to be deasserted in LP-11 mode
>  (2) For I2C access the bridge needs the DSI clock
>  (3) The bridge has to be configured while the video stream is
>      disabled.
>  (4) The bridge has limitations on the display timings. In particular,
>      the horizontal pulse width has to be at least 8 pixels wide and
>      both the horizontal pulse width as well as the back porch has to
>      be even. According to the datasheet the horizontal front porch as
>      well but in line sync mode, this is ignored. Also line sync is the
>      only supported mode for this bridge, therefore, the front porch
>      is always ignored.
>
> The most controversial patch is probably "drm/bridge: add
> dsi_lp11_notify mechanism" which is needed for (1) above. Some time ago
> there was a series [1] to add a manual power-up, which was abandoned and
> which didn't suite the needs for this bridge anyway.
>
> Also, this will gradually change the tc_ prefix to tc358775_ while the
> functions are refactored.
>
> The bridge was successfully tested on a Mediatek MT8195 SoC with the
> following panels:
>  - Innolux G101ICE
>  - AUO G121EAN01.0
>  - Innolux G156HCE (dual-link LVDS)
>
> [1] https://lore.kernel.org/r/20231016165355.1327217-1-dmitry.baryshkov@linaro.org/

Any comments on this series, besides the discussion on how to do the
reset during LP11?

Most of the other patches should be more or less self contained.

-michael

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