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

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Date:   Wed, 4 Jan 2023 11:17:32 +0800
From:   Baochen Qiang <quic_bqiang@...cinc.com>
To:     Jeffrey Hugo <jeffrey.l.hugo@...il.com>
CC:     <manivannan.sadhasivam@...aro.org>,
        <linux-arm-msm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <ath11k@...ts.infradead.org>, <mhi@...ts.linux.dev>
Subject: Re: [PATCH] bus: mhi: host: Change the log levels for SYS_ERR event


On 1/4/2023 11:11 AM, Jeffrey Hugo wrote:
> 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


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