Re: [PATCH 2/8] bus: fsl-mc: handle DMA config deferral in ACPI case

[Daniel Thompson]

Hi Laurentiu

On Thu, Jul 15, 2021 at 05:07:12PM +0300, laurentiu.tudor@xxxxxxx wrote:
> From: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>
> 
> ACPI DMA configure API may return a defer status code, so handle it.
> On top of this, move the MC firmware resume after the DMA setup
> is completed to avoid crashing due to DMA setup not being done yet or
> being deferred.
> 
> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@xxxxxxx>

I saw regressions on my Honeycomb LX2 (NXP LX2060A) when I switched to
v5.15. It seems like it results in so many sMMU errors that the system
cannot function correctly (it's only about a 75% chance the system will
boot to GUI and even if it does boot successfully the system will hang
up soon after).

Bisect took me up a couple of blind alleys (mostly due to unrelated boot
problems in v5.14-rc2) by eventually led me to this patch as the cause.
Applying/unapplying this patch to a v5.14-rc3 tree will provoke/fix the
problem and reverting it against v5.15 also resolves the problem.

Is there some specific firmware version required for this patch to work
correctly?


Daniel.


PS: Below is the revert I applied to the v5.15 kernel (after
    a fairly simple merge conflict fix)