linux-kernel - Re: [PATCH] remoteproc: qcom: Add NOTIFY

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Date:   Sat, 25 Nov 2023 00:24:38 +0530
From:   Vignesh Viswanathan <quic_viswanat@...cinc.com>
To:     Bjorn Andersson <andersson@...nel.org>
CC:     <agross@...nel.org>, <konrad.dybcio@...aro.org>,
        <mathieu.poirier@...aro.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-remoteproc@...r.kernel.org>,
        <quic_srichara@...cinc.com>, <quic_varada@...cinc.com>,
        <quic_kathirav@...cinc.com>, <quic_devipriy@...cinc.com>,
        <quic_sjaganat@...cinc.com>
Subject: Re: [PATCH] remoteproc: qcom: Add NOTIFY_FATAL event type to SSR
 subdevice



On 9/4/2023 10:23 PM, Vignesh Viswanathan wrote:
> 
> 
> On 7/16/2023 1:50 AM, Bjorn Andersson wrote:
>> On Wed, May 03, 2023 at 11:51:46AM +0530, Vignesh Viswanathan wrote:
>>> Currently the SSR subdevice notifies the client driver on crash of the
>>> rproc from the recovery workqueue using the BEFORE_SHUTDOWN event.
>>> However the client driver might be interested to know that the device
>>> has crashed immediately to pause any further transactions with the
>>> rproc. This calls for an event to be sent to the driver in the IRQ
>>> context as soon as the rproc crashes.
>>>
>>
>> Please make your argumentation more concrete, I can only guess what
>> client driver you're referring to.
>>
>> You can do this either by spelling out which actual problem you're
>> solving, or better yet, include some patches in the series that actually
>> uses this interface.
>>
> 
> Hi Bjorn,
> 
> Apologies for the delay in response.
> 
> The client driver in my scenario is a Wi-Fi driver which is continuously
> queuing data to the remoteproc and needs to know if remoteproc crashes
> as soon as possible to stop queuing further data and also dump some 
> debug statistics on the driver side that could potentially help in debug
> of why the remoteproc crashed.
> 
> Also in the case with upcoming Wi-Fi 7 targets with multi-link 
> operation, the driver might need to know that the remoteproc has crashed
> instantly to handle some multi-link specific handling.
> 
> The ath11k/ath12k WLAN drivers today partially have support for handling
> such FATAL notification but it has not been upstreamed yet.
> 
> Reference patch: 
> https://git.codelinaro.org/clo/qsdk/oss/system/feeds/wlan-open/-/blob/win.wlan_host_opensource.1.0/mac80211/patches/031-ath11k-print-stats-on-crash.patch -- event SUBSYS_PREPARE_FOR_FATAL_SHUTDOWN.
> 
> Also, Mukesh mentioned earlier that in some MSM targets with PCIe where 
> latency cannot be tolerated, a similar downstream patch adds support for 
> "early notifier". If this patch is accepted, the early notifier can also 
> be replaced to use the same NOTIFY_FATAL event from SSR Subdevice
> 
> https://git.codelinaro.org/clo/la/kernel/msm-5.15/-/commit/7583d24de337aa1bf7c375a7da706af9b995b9a1#a840754ebb0e24e88adbf48177e1abd0830b72d2
> https://git.codelinaro.org/clo/la/kernel/msm-5.15/-/commit/257de41c63a5a51a081cc7887cdaa4a46e4d1744

Hi Bjorn,

Gentle reminder for this patch.

Thanks,
Vignesh
> 
> Thanks,
> Vignesh
> 
>> Regards,
>> Bjorn