Re: [PATCH RFC] ARM: dts: bcm2711: Fix DMA constrains for newer BCM2711 boards

[Florian Fainelli <f.fainelli@gmail.com>]

On 5/4/2022 2:43 PM, Stefan Wahren wrote:
> Hi,
> 
> Am 13.04.22 um 18:27 schrieb Stefan Wahren:
>> The commit 3d2cbb644836 ("ARM: dts: bcm2711: Move emmc2 into its own 
>> bus")
>> assumed that all bootloader pass the FDT modified by the firmware to the
>> kernel. But this is not always the case (e.g. Fedora) and cause boot
>> issues for boards with a BCM2711 C0 SoC (RPi 400, CM4, newer RPi 4 B)
>> which does have different DMA constraints.
>>
>> Since we are not able to detect the SoC revision, let's assume a BCM2711
>> C0 SoC for bcm2711.dtsi and move the restricted DMA constrains to a
>> separate RPi 4 B board file just for the old SoC revision.
>>
>> Fixes: 3d2cbb644836 ("ARM: dts: bcm2711: Move emmc2 into its own bus")
>> Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
> since there wasn't any feedback yet, i want to ping ...

Could not we just rely on the VPU patching the Device Tree instead of 
having to differentiate the 2711 revision and having to use different 
DTS/DTBs?

Also, can we consider that the older B0 are less predominant in the wild 
than the C0 nowadays, especially with the shortages going on is that 
even remotely the case?
-- 
Florian