[PATCH] video: rockchip: Add missing dpcd_write() call to link_train_ce()

[Alper Nebi Yasak]

On 15/10/2020 10:19, Arnaud Patard (Rtp) wrote:
> Alper Nebi Yasak <alpernebiyasak at gmail.com> writes:
>> I'm not sure re-porting is a great idea from the technical perspective.
>> I've been reading both drivers to compare them, there are also things in
>> U-Boot that're missing from coreboot. Things like DM integration are
>> also not there as they're U-Boot specific.
> 
> I think it would be better to use fixes from the kernel or coreboot (if
> license allows it) than copying coreboot blindly. Doing that will
> possibly regress support from some systems as I fear that coreboot is
> missing some HW support.

I was planning on picking changes that look like improvements, yeah.

> tbh, I've not looked at the coreboot code but given most HW vendor
> history, it would be not so surprising that only the support for what's
> needed on kevin or bob (EDP and CDN DP or HDMI on rk3399) has been added
> to coreboot.

I could only find veyron-based and gru-based Chrome OS devices (but the
latter also includes gru-scarlet w/ MIPI), as their vendor firmware is
coreboot-based. I'd guess other vendors are more focused on U-Boot.

> I've also seen some uboot sources with rockchip linux drm code
> [1]. I've no idea if it's used in practice but this means that people may
> even ask "Why merging coreboot code while it's possible to use linux drm
> code ?" ...

AFAIK, Rockchip-downstream U-Boot [2] does it that way. Maybe that's not
being done upstream for e.g. code size reasons?

[2] https://github.com/rockchip-linux/u-boot/