linux-kernel - Re: [RFC PATCH 2/9] drm: bridge: Add Samsung SEC MIPI DSIM bridge driver

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Date:   Mon, 28 Jun 2021 10:19:50 +0200
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Fabio Estevam <festevam@...il.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Michael Tretter <m.tretter@...gutronix.de>
Cc:     Jagan Teki <jagan@...rulasolutions.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Peng Fan <peng.fan@....com>,
        Francis Laniel <francis.laniel@...rulasolutions.com>,
        Matteo Lisi <matteo.lisi@...icam.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-amarula <linux-amarula@...rulasolutions.com>,
        Tomasz Figa <t.figa@...sung.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Robert Foss <robert.foss@...aro.org>,
        Andrzej Hajda <a.hajda@...sung.com>,
        DRI mailing list <dri-devel@...ts.freedesktop.org>,
        Milco Pratesi <milco.pratesi@...icam.com>,
        Anthony Brandon <anthony@...rulasolutions.com>,
        linux-phy@...ts.infradead.org, Fancy Fang <chen.fang@....com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        NXP Linux Team <linux-imx@....com>,
        "marex@...x.de" <marex@...x.de>,
        Daniel Vetter <daniel.vetter@...el.com>
Subject: Re: [RFC PATCH 2/9] drm: bridge: Add Samsung SEC MIPI DSIM bridge
 driver

Hi Jagan,

On 24.06.21 10:30, Krzysztof Kozlowski wrote:
> On 24/06/2021 04:48, Fabio Estevam wrote:
>> Hi Jagan/Laurent,
>>
>> On Wed, Jun 23, 2021 at 7:23 PM Laurent Pinchart
>> <laurent.pinchart@...asonboard.com> wrote:
>>
>>> Looking at the register set, it seems to match the Exynos 5433,
>>> supported by drivers/gpu/drm/exynos/exynos_drm_dsi.c. Can we leverage
>>> that driver instead of adding a new one for the same IP core ?
>>
>> Yes. there was an attempt from Michael in this direction:
>> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwork.kernel.org%2Fproject%2Fdri-devel%2Fcover%2F20200911135413.3654800-1-m.tretter%40pengutronix.de%2F&amp;data=04%7C01%7Cfrieder.schrempf%40kontron.de%7C52db05459ef0462d5a9b08d936eab1ba%7C8c9d3c973fd941c8a2b1646f3942daf1%7C0%7C0%7C637601203901391193%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=LTYk9kpUeB9bgfRITQT6wIij3XTOIk37AHXbzQ2UI4Y%3D&amp;reserved=0
> 
> That's the proper direction (maybe as Marek suggested - sharing common
> code like for Analogix DP), not duplicating a driver.
> 

Just to make sure that you are aware of the previous patches and discussions here are some additional pointers:

* i.MX8MM glue code from Marek (+ Cc): [1]
* DPHY driver from Marek: [2]
* General discussion about driver implementation: [3]
* Daniel's (+ Cc) suggested direction to move forward: [4]

It looks like you already did a fork of the Exynos driver, so your approach might be generally in line with what Daniel suggested.

Best regards
Frieder

[1] https://patchwork.kernel.org/project/linux-arm-kernel/patch/20201005134250.527153-3-marex@denx.de/
[2] https://patchwork.kernel.org/project/linux-arm-kernel/patch/20201003225020.164358-1-marex@denx.de/
[3] https://patchwork.kernel.org/project/dri-devel/patch/20200911135413.3654800-11-m.tretter@pengutronix.de/
[4] https://patchwork.kernel.org/project/dri-devel/patch/20200911135413.3654800-11-m.tretter@pengutronix.de/#23995147