linux-kernel - Re: [PATCH] bus: mhi: host: Change the log levels for SYS

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Message-ID: <CAOCk7NqNrxcXLsw3PRRdsiOrq5SB9DfxpuSH84-rB9-43fdpog@mail.gmail.com>
Date:   Tue, 3 Jan 2023 20:11:22 -0700
From:   Jeffrey Hugo <jeffrey.l.hugo@...il.com>
To:     Baochen Qiang <quic_bqiang@...cinc.com>
Cc:     manivannan.sadhasivam@...aro.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, ath11k@...ts.infradead.org
Subject: Re: [PATCH] bus: mhi: host: Change the log levels for SYS_ERR event

On Tue, Jan 3, 2023 at 7:57 PM Baochen Qiang <quic_bqiang@...cinc.com> 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@...aro.org>
L: mhi@...ts.linux.dev
L: linux-arm-msm@...r.kernel.org
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@...cinc.com> 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