Re: bcm2711 / RPi4 not functional after d62069c22eda

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

On 3/18/2022 5:59 AM, Lukas Wunner wrote:
> [cc += linux-spi; please do not write developers directly without cc'ing
> relevant lists]
> 
> On Fri, Mar 18, 2022 at 11:54:35AM +0100, Miguel Angel Ajo wrote:
>> On Fri, Mar 18, 2022 at 11:47 AM Miguel Angel Ajo <majopela@redhat.com>
>> wrote:
>>>      I wanted to share a regression found after commit:
>>>
>>> d62069c22eda spi: bcm2835: Remove shared interrupt support
> [...]
>>> After this commit I get:
>>>
>>> [root@rpi4-64 ~]# dmesg | grep spi
>>> [   18.781250] spi-bcm2835 fe204000.spi: could not register SPI
>>> controller: -517
>>> [   19.134138] spi-bcm2835 fe204000.spi: could not register SPI
>>> controller: -517
>>> [   19.895147] spi-bcm2835 fe204000.spi: could not register SPI
>>> controller: -517
>>> [   20.400137] spi-bcm2835 fe204000.spi: could not register SPI
>>> controller: -517
> 
> Those are transient errors, -517 is -EPROBE_DEFER.  Probing fails
> because a resource is not available (yet), to be retried again later
> if/when it becomes available.

You would want to check whether you have these two commits in your tree 
as well:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=266423e60ea1b953fcc0cd97f3dad85857e434d1
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e8f24c58d1b69ecf410a673c22f546dc732bb879

or neither, because the first commit forces a lockstep update of the DTS.

The SPI driver does not uses that many shared resources besides 
interrupts, clocks and chip-select overs GPIOs, the first one is 
unlikely to be the problem, and so is the second, thus leaving the third 
resource as a candidate to defer on.

> 
> 
>>> ecfbd3c introduced support for the bcm2711 SoC that shares
>>> one interrupt over multiple spi controller instances.
>>>
>>> Do we have a more detailed description of the exact issue for
>>> which we reverted?, is there a plan to re-introduce the shared interrupt
>>> support while fixing the issue?
> 
> See here for why the commit was reverted:
> 
> https://lore.kernel.org/linux-spi/20200529174358.som3snunfxch6phi@wunner.de/
> 
> There was a second attempt to introduce shared interrupt support,
> but after a lengthy discussion, it was not pursued to fruition:
> 
> https://lore.kernel.org/linux-spi/20200604212819.715-1-f.fainelli@gmail.com/
> 
> So I believe shared interrupt support only exists in the Raspberry Pi
> Foundation's downstream kernel, but not yet in the mainline kernel.
> 
> Thanks,
> 
> Lukas

-- 
Florian