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: <9c59661e-98e6-473e-9a5e-b6002048c51a@mailbox.org>
Date: Tue, 13 Jan 2026 10:15:16 +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 9:15 AM, Joseph Guo wrote:
> On 1/13/2026 4:04 PM, Marek Vasut wrote:
>> [You don't often get email from marek.vasut@...lbox.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>>
>> Caution: This is an external email. Please take care when clicking links or opening attachments. When in doubt, report the message using the 'Report this email' button
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>> On 1/13/26 7:41 AM, Joseph Guo wrote:
>>> On 1/13/2026 7:47 AM, Marek Vasut wrote:
>>>> [You don't often get email from marek.vasut+renesas@...lbox.org. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>>>>
>>>> Caution: This is an external email. Please take care when clicking links or opening attachments. When in doubt, report the message using the 'Report this email' button
>>>>
>>>>
>>>> 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"
> 
> OK, thank you.
> Reviewed-by: Joseph Guo <qijian.guo@....com>
Thank you too.