Re: [PATCH] remoteproc: qcom: Add NOTIFY_FATAL event type to SSR subdevice

[Vignesh Viswanathan]

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