Re: [DEBUG PATCH] brcmfmac: add firmware watchdog running on host machine

[Arend van Spriel <arend.vanspriel@broadcom.com>]

On 8/15/2018 8:01 PM, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
>
> It may happen for FullMAC firmware to crash. It should be detected and
> ideally somehow handled by a driver.
>
> Since commit ff4445a8502c ("brcmfmac: expose device memory to
> devcoredump subsystem") brcmfmac has BRCMF_E_PSM_WATCHDOG event handler
> but it wasn't enough to detect all kind of crashes. E.g. Netgear R8000
> (BCM4709A0 + 3 x BCM43602) user was exepriencing firmware crashes that
> never resulted in passing BRCMF_E_PSM_WATCHDOG to the host driver.

Thanks, Rafał

The PSM watchdog is actually not a firmware crash. It means the lower 
part of the stack, which runs in the d11 core aka PSM, did not complete 
its work in the required timing budget.

> That made me implement this trivial software watchdog that simply checks
> periodically if firmware still replies to the commands.
>
> Luckily this patch DOES NOT seem to be needed anymore since the commit
> 8a3ab2f38f16 ("brcmfmac: trigger memory dump upon firmware halt
> signal"). That change allows brcmfmac to detect firmware crashes
> successfully.

It can still miss a firmware crash if it happens really soon. Those 
crashes mostly happens when trying to load firmware for chip revision A 
on chip with revision B due to differences in code contained in ROM.

Regards,
Arend

> This patch is being posted for research/debugging purposes only. It
> SHOULD NOT be applied until someone notices a firmware crash that
> doesn't trigger the BRCMF_D2H_DEV_FWHALT signal.
>
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---