Re: mhi resume failure on reboot with 6.13-rc2

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Wed, Dec 11, 2024 at 04:03:59PM +0100, Johan Hovold wrote:
> On Wed, Dec 11, 2024 at 08:23:15PM +0530, Manivannan Sadhasivam wrote:
> > On Wed, Dec 11, 2024 at 03:17:22PM +0100, Johan Hovold wrote:
> 
> > > I just hit the following modem related error on reboot of the x1e80100
> > > CRD for the second time with 6.13-rc2:
> > > 
> > > 	[  138.348724] shutdown[1]: Rebooting.
> > >         [  138.545683] arm-smmu 3da0000.iommu: disabling translation
> > >         [  138.582505] mhi mhi0: Resuming from non M3 state (SYS ERROR)
> > >         [  138.588516] mhi-pci-generic 0005:01:00.0: failed to resume device: -22
> > >         [  138.595375] mhi-pci-generic 0005:01:00.0: device recovery started
> > >         [  138.603841] wwan wwan0: port wwan0qcdm0 disconnected
> > >         [  138.609508] wwan wwan0: port wwan0mbim0 disconnected
> > >         [  138.615137] wwan wwan0: port wwan0qmi0 disconnected
> > >         [  138.702604] mhi mhi0: Requested to power ON
> > >         [  139.027494] mhi mhi0: Power on setup success
> > >         [  139.027640] mhi mhi0: Wait for device to enter SBL or Mission mode
> > > 
> > > and then the machine hangs.
> > > 
> > > Do you know if there are any changes since 6.12 that could cause this?
> > 
> > Only 3 changes went in for 6.13-rc1 and they shouldn't cause any issues. One
> > caused the regression with pcim_iomap_region(), but you submitted a fix for
> > that and other two were trivial.
> 
> Ok, thanks.
> 
> > From the log, 'mhi mhi0: Resuming from non M3 state (SYS ERROR)' indicates that
> > the firmware got crashed while resuming. So maybe you should check with ath12k
> > folks.
> 
> This is the modem so I don't think the ath12k wifi folks are to blame
> here.
> 

Ah, even after these years I always confuse between WLAN and WWAN :)

> It may be an older, existing issue that started triggering due to
> changes in timing or something.
>

Could be. But the issue seems to be stemming from the modem crash while exiting
M3. You can try removing the modem autosuspend by skipping the if condition
block:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/bus/mhi/host/pci_generic.c?h=v6.13-rc1#n1184

If you no longer see the crash, then the issue might be with modem not coping
up with autosuspend. If you still see the crash, then something else going wrong
during reboot/power off.

> Is there anything you can do on the mhi side to prevent it from blocking
> reboot/power off?
> 

It should not block the reboot/power off forever. There is a timeout waiting for
SBL/Mission mode and the max time is 24s (depending on the modem). Can you share
the modem VID:PID?

- Mani

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