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Date:   Thu, 20 Aug 2020 17:18:26 +0800
From:   Wen Gong <wgong@codeaurora.org>
To:     Kalle Valo <kvalo@codeaurora.org>
Cc:     ath10k@lists.infradead.org, linux-wireless@vger.kernel.org
Subject: Re: [PATCH v4 1/2] ath10k: add refcount for ath10k_core_restart
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 <20200108031957.22308-2-wgong@codeaurora.org>
 <87imdlkuw8.fsf@codeaurora.org>
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On 2020-08-15 01:19, Kalle Valo wrote:
...
> 
> I have been thinking a different approach for this. I think another
> option is to have a function like this:
> 
> ath10k_core_firmware_crashed()
> {
>         queue_work(ar->workqueue, &ar->restart_work);
> }
> 
> In patch 1 we would convert all existing callers to call that
> function instead of queue_work() directly.
> 
> In patch 2 we would add a new flag to enum ath10k_dev_flags, or maybe
> should actually use existing ATH10K_FLAG_CRASH_FLUSH? Don't know yet
> which one is better. Now the function would do:
I thinks we can use test_and_set_bit for atomic operation athough it is 
same with restart_count.
and add a new flag, ATH10K_FLAG_CRASH_FLUSH is used for flush,
if still use ATH10K_FLAG_CRASH_FLUSH, it should change clear_bit of it 
from
ath10k_core_start to ath10k_reconfig_complete,because 
ieee80211_reconfig(called by
ieee80211_restart_work)
of mac80211 do many things and drv_start is 1st thing and
drv_reconfig_complete is last thing, drv_reconfig_complete done means 
the restart
finished.

I will send patch v5 with above changes if not other advise.
> 
> ath10k_core_firmware_crashed()
> {
>         if (test_bit(flag))
>                 return
> 
>         set_bit(flag)
> 	queue_work(ar->workqueue, &ar->restart_work);
> }
> 
> That way restart_work queue would be called only one time.
> 
> Though I'm not sure how ATH10K_STATE_WEDGED would behave after this
> change, it might get broken. Ah, actually I think even this patch 
> breaks
> the WEDGED state. This firmware restart is tricky, difficult to say 
> what
> is the best approach. Michal, are you reading? :) Any ideas?
> 
> And after looking more about this patch I don't see the need for the 
> new
> ar->restart_count atomic variable. Checking for ATH10K_FLAG_CRASH_FLUSH
> would do the same thing AFAICS.
> 
> And related to this, (in a separate patch) I think we should utilise
> ATH10K_FLAG_CRASH_FLUSH more. For example in ath10k_wmi_cmd_send() to
> not even try to send a WMI command if the flag is set. Basically all
> hardware access should be disabled except what is needed to restart the
> firmware.