Re: [PATCH] bus: mhi: host: Change the log levels for SYS_ERR event

[Baochen Qiang]

On 1/4/2023 11:11 AM, Jeffrey Hugo wrote:
> On Tue, Jan 3, 2023 at 7:57 PM Baochen Qiang <quic_bqiang@xxxxxxxxxxx> wrote:
> > On 1/4/2023 10:41 AM, Jeffrey Hugo wrote:
> > > Why was this not sent to the MHI mailing list?
> > I don't know the MHI mailing list address, could tell me that?
> The relevant entry from MAINTAINERS -
>
> MHI BUS
> M: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> L: mhi@xxxxxxxxxxxxxxx
> L: linux-arm-msm@xxxxxxxxxxxxxxx
> S: Maintained
> T: git git://git.kernel.org/pub/scm/linux/kernel/git/mani/mhi.git
> F: Documentation/ABI/stable/sysfs-bus-mhi
> F: Documentation/mhi/
> F: drivers/bus/mhi/
> F: include/linux/mhi.h
>
> > > On Tue, Jan 3, 2023 at 7:19 PM Baochen Qiang <quic_bqiang@xxxxxxxxxxx> wrote:
> > > > Currently no log printed when SYS_ERR happens, this makes
> > > > debug quite hard, so change log level to make it noisy.
> > > You are going to need to explain this more.
> > > There are two drivers in the upstream kernel that are MHI clients -
> > > pci_generic and ath11k.
> > > I'm assuming that you care about ath11k because you included that mail list.
> > Yes, I am talking about ath11k.
> > > In ath11k_mhi_op_status_cb() I see a warning message printed when the
> > > syserr callback is triggered.
> > > I see something similar in pci_generic.
> > >
> > > Looks like a log is printed when SYS_ERR happens in all possible
> > > scenarios, so I don't understand the point of this change.
> > > Particularly given that dev_dbg messages can be trivially enabled.
> > >
> > > -Jeff
> > Well, this is not true in some cases. For example, we have met cases where
> >
> > WLAN HW/firmware is not working well, and only send a SYS_ERR event to MHI
> >
> > driver, however this event is not sent to ath11k host becuase of
> > mhi_pm_sys_err_handler(),
> >
> > so we got no log at all.
> With the 6.1 kernel?
>
> mhi_pm_sys_err_handler() queues the st_worker.
>
> mhi_pm_st_worker() , which is the st_worker function, calls
> mhi_pm_sys_error_transition() in the DEV_ST_TRANSITION_SYS_ERR case
> (we are processing a SYS_ERR).
>
> Pretty much the first thing mhi_pm_sys_err_transition() does is this -
>
> /* We must notify MHI control driver so it can clean up first */
> mhi_cntrl->status_cb(mhi_cntrl, MHI_CB_SYS_ERROR);
>
> Which calls the ath11k driver ath11k_mhi_op_status_cb() I mentioned earlier.
>
> -Jeff


No, mhi_pm_sys_err_handler() will NOT queue the st_worker because ath11k 
host supports RDDM, so the SYS_ERR event will be skipped. See below log:

kernel: [  165.393720] mhi mhi0: local ee: MISSION MODE state: M0 device 
ee: RAMDUMP DOWNLOAD MODE state: M0
kernel: [  165.401820] mhi mhi0: State change event to state: SYS ERROR
kernel: [  165.401824] mhi mhi0: System error detected
kernel: [  165.401827] mhi mhi0: Controller supports RDDM, skip SYS_ERROR