[EXT] Re: [PATCH 1/9] dt-bindings: mxsfb: Add compatible for i.MX8MP

[Robby Cai]

>-----Original Message-----
>From: Marek Vasut <marex at denx.de>
>Sent: 2022年3月2日 10:50
>To: Robby Cai <robby.cai at nxp.com>; Lucas Stach <l.stach at pengutronix.de>;
>Adam Ford <aford173 at gmail.com>
>Cc: Ying Liu (OSS) <victor.liu at oss.nxp.com>; dri-devel
><dri-devel at lists.freedesktop.org>; devicetree <devicetree at vger.kernel.org>;
>Peng Fan <peng.fan at nxp.com>; Alexander Stein
><alexander.stein at ew.tq-group.com>; Rob Herring <robh+dt at kernel.org>;
>Laurent Pinchart <laurent.pinchart at ideasonboard.com>; Sam Ravnborg
><sam at ravnborg.org>
>Subject: Re: [EXT] Re: [PATCH 1/9] dt-bindings: mxsfb: Add compatible for
>i.MX8MP
>
>Caution: EXT Email
>
>On 3/1/22 14:37, Robby Cai wrote:
>
>Hi,
>
>[...]
>
>>>> I tend to agree with Marek on this one.  We have an instance where
>>>> the blk-ctrl and the GPC driver between 8m, mini, nano, plus are
>>>> close, but different enough where each SoC has it's own set of tables and
>>>> some checks.   Lucas created the framework, and others adapted it for
>>>> various SoC's.  If there really is nearly 50% common code for the
>>>> LCDIF, why not either leave the driver as one or split the common
>>>> code into its own driver like lcdif-common and then have smaller
>>>> drivers that handle their specific variations.
>>>
>>> I don't know exactly how the standalone driver looks like, but I
>>> guess the overlap is not really in any real HW specific parts, but
>>> the common DRM boilerplate, so there isn't much point in creating a
>common lcdif driver.
>>>
>>> As you brought up the blk-ctrl as an example: I'm all for supporting
>>> slightly different hardware in the same driver, as long as the HW
>>> interface is close enough. But then I also opted for a separate 8MP
>>> blk-ctrl driver for those blk-ctrls that differ significantly from
>>> the others, as I think it would make the common driver unmaintainable
>>> trying to support all the different variants in one driver.
>>>
>>> Regards,
>>> Lucas
>>
>> LCDIF on i.MX8MP is a different IP which is borrowed from non-iMX series,
>although it's also called 'LCDIF'.
>> We prefer not mix these two series of IPs in one driver for ease of
>maintenance and extension.
>
>Where does the MX8MP LCDIF come from then, SGTL maybe ?

AFAIK, it's RT1170. You may have a check on RM [1]. Interestingly, this SoC has both eLCDIF and LCDIFv2, two IPs we are talking about.

[1] https://www.nxp.com/webapp/Download?colCode=IMXRT1170RM

Regards,
Robby