linux-kernel - Re: [EXT] [PATCH 2/2] drm/bridge: waveshare-dsi: Add support for 1..4 DSI data lanes

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Message-ID: <65ccfeb6-4962-4964-be1d-cfb0ed41773e@mailbox.org>
Date: Tue, 13 Jan 2026 09:04:17 +0100
From: Marek Vasut <marek.vasut@...lbox.org>
To: Joseph Guo <qijian.guo@....com>, dri-devel@...ts.freedesktop.org
Cc: Andrzej Hajda <andrzej.hajda@...el.com>,
 Conor Dooley <conor+dt@...nel.org>, David Airlie <airlied@...il.com>,
 Jernej Skrabec <jernej.skrabec@...il.com>, Jonas Karlman <jonas@...boo.se>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>,
 Neil Armstrong <neil.armstrong@...aro.org>, Rob Herring <robh@...nel.org>,
 Robert Foss <rfoss@...nel.org>, Simona Vetter <simona@...ll.ch>,
 Thomas Zimmermann <tzimmermann@...e.de>, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org
Subject: Re: [EXT] [PATCH 2/2] drm/bridge: waveshare-dsi: Add support for 1..4
 DSI data lanes

On 1/13/26 7:41 AM, Joseph Guo wrote:
> On 1/13/2026 7:47 AM, Marek Vasut wrote:
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>>
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>>
>> Parse the data lane count out of DT. Limit the supported data lanes
>> to 1..4 which is the maximum available DSI pairs on the connector of
>> any known panels which may use this bridge. Internally, this bridge
>> is an ChipOne ICN6211 which loads its register configuration from a
>> dedicated storage and its I2C does not seem to be accessible. The
>> ICN6211 also supports up to 4 DSI lanes, so this is a hard limit.
>>
>> To avoid any breakage on old DTs where the parsing of data lanes from
>> DT may fail, fall back to the original hard-coded value of 2 lanes and
>> warn user.
>>
>> The lane configuration is preconfigured in the bridge for each of the
>> WaveShare panels. The 13.3" DSI panel works with 4-lane configuration,
>> others seem to use 2-lane configuration. This is a hardware property,
>> so the actual count should come from DT.
>>
>>
> Hi Marek,
> 
> I don't have 4 lanes waveshare panel on my hands. Have you tested with the 4-lane panel already?
Yes, the 13.3" DSI panel is 4-lane 
https://www.waveshare.com/13.3inch-dsi-lcd.htm , I have it connected to 
Retronix Sparrow Hawk board which has 4-lane port.

See also this patch I submitted, that is the DT binding for it:

[PATCH 2/2] arm64: dts: renesas: sparrow-hawk: Add overlay for WaveShare 
Display 13.3"