Re: Raspberry Pi 4 support on 32 bit earmv7hf GENERIC kernel

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

> This will fix your problem I think (and do the cleanup I promised a while back)
> 
> https://www.netbsd.org/~skrll/rpi.fb.diff

Thanks for the diff.

I see the direction you are taking here.  If this is the preferred
approach, I have no objection to handling it that way instead of
going through the /chosen/simple-framebuffer path.

For RPI 1/Zero/2/3 (i.e. bcm2835/bcm2836/bcm2837), "brcm,bcm2835-fb"
already comes from bcm2835-common.dtsi, so I am not yet sure
the extra local wrapper DTS files are needed there as part of
this change.

So I would prefer to keep this change limited to the bcm2711 board
DTS files: bcm2711-rpi-4-b.dts, bcm2711-rpi-400.dts, and
bcm2711-rpi-cm4-io.dts.

I still have one concern about BGR/RGB handling in this approach:

- The firmware provides "format" property such as "a8r8g8b8" via
  dynamically populated "/chosen/framebuffer" node.

- But rpi_fb_init() in bcm283x_platform.c seems to determine
  BGR vs RGB from the bootconf option "bcm2708_fb.fbswap".
  in bcm283x_platform.c.

- It looks like RPI4 firmware does not provide that bootconf option,
  so the default "is_bgr" value would be used.

Thanks,
---
Izumi Tsutsui