[PATCH 3/3] ath10k: speed up hw recovery

[Michal Kazior]

On 13 October 2014 10:15, Kalle Valo <kvalo at qca.qualcomm.com> wrote:
> Michal Kazior <michal.kazior at tieto.com> writes:
>
>> In some cases hw recovery was taking an absurdly
>> long time due to ath10k waiting for things that
>> would never really complete.
>>
>> Instead of waiting for inevitable timeouts poke
>> all completions and wakequeues and check if it's
>> still worth waiting.
>>
>> Signed-off-by: Michal Kazior <michal.kazior at tieto.com>
>
> [...]
>
>> --- a/drivers/net/wireless/ath/ath10k/core.c
>> +++ b/drivers/net/wireless/ath/ath10k/core.c
>> @@ -685,6 +685,20 @@ static void ath10k_core_restart(struct work_struct *work)
>>  {
>>       struct ath10k *ar = container_of(work, struct ath10k, restart_work);
>>
>> +     set_bit(ATH10K_FLAG_CRASH_FLUSH, &ar->dev_flags);
>> +     barrier();
>
> Please document why the barrier is needed.

Okay. It's just to make sure compiler doesn't re-order it (so that
following complete/wake_ups will be called _after_ the bit is set).


>> --- a/drivers/net/wireless/ath/ath10k/core.h
>> +++ b/drivers/net/wireless/ath/ath10k/core.h
>> @@ -371,6 +371,11 @@ enum ath10k_dev_flags {
>>       /* Indicates that ath10k device is during CAC phase of DFS */
>>       ATH10K_CAC_RUNNING,
>>       ATH10K_FLAG_CORE_REGISTERED,
>> +
>> +     /* Device has crashed and needs to restart. This indicates any pending
>> +      * waiters should immediately cancel instead of waiting for a time out.
>> +      */
>> +     ATH10K_FLAG_CRASH_FLUSH,
>>  };
>
> Instead of a dev flag, should this actually be a new state to enum
> ath10k_state? The reason I ask, I don't see how we would use this flag
> with other states than with ATH10K_STATE_ON. Or is this needed because
> of locking?

Locking.

Reading/writing ar->state requires conf_mutex. The problem is waitiers
might be holding it so you wouldn't even be able to tell the waiters
to not wait anymore.

A long term idea might involve removing conf_mutex though but I recall
there's a couple of problems with that when I looked at it.


Michał