linux-kernel - Re: [PATCH] ath10k: Keep track of which interrupts fired, don't poll them

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Date:   Wed, 8 Jul 2020 16:14:18 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Brian Norris <briannorris@...omium.org>
Cc:     Kalle Valo <kvalo@...eaurora.org>,
        ath10k <ath10k@...ts.infradead.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Rakesh Pillai <pillair@...eaurora.org>,
        Abhishek Kumar <kuabhs@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        "<netdev@...r.kernel.org>" <netdev@...r.kernel.org>
Subject: Re: [PATCH] ath10k: Keep track of which interrupts fired, don't poll them

Hi,

On Wed, Jul 8, 2020 at 4:03 PM Brian Norris <briannorris@...omium.org> wrote:
>
> On Tue, Jul 7, 2020 at 10:18 AM Douglas Anderson <dianders@...omium.org> wrote:
> > diff --git a/drivers/net/wireless/ath/ath10k/ce.h b/drivers/net/wireless/ath/ath10k/ce.h
> > index a440aaf74aa4..666ce384a1d8 100644
> > --- a/drivers/net/wireless/ath/ath10k/ce.h
> > +++ b/drivers/net/wireless/ath/ath10k/ce.h
> ...
> > @@ -376,12 +377,9 @@ static inline u32 ath10k_ce_interrupt_summary(struct ath10k *ar)
> >  {
> >         struct ath10k_ce *ce = ath10k_ce_priv(ar);
> >
> > -       if (!ar->hw_params.per_ce_irq)
>
> If I'm reading correctly, you're removing the only remaining use of
> 'per_ce_irq'. Should we kill the field entirely?

Ah, you are indeed correct!  I hadn't noticed that.  Unless I hear
otherwise, I'll send a v2 tomorrow that removes the field entirely.


> Or perhaps we should
> leave some kind of WARN_ON() (BUG_ON()?) if this function is called
> erroneously with per_ce_irq==true? But I suppose this driver is full
> of landmines if the CE API is used incorrectly.

Yeah, I originally had a WARN_ON() here and then took it out because
it seemed like extra overhead and, as you said, someone writing the
code has to know how the API works already I think.  ...but I'll add
it back in if people want.


> > -               return CE_WRAPPER_INTERRUPT_SUMMARY_HOST_MSI_GET(
> > -                       ce->bus_ops->read32((ar), CE_WRAPPER_BASE_ADDRESS +
> > -                       CE_WRAPPER_INTERRUPT_SUMMARY_ADDRESS));
> > -       else
> > -               return ath10k_ce_gen_interrupt_summary(ar);
> > +       return CE_WRAPPER_INTERRUPT_SUMMARY_HOST_MSI_GET(
> > +               ce->bus_ops->read32((ar), CE_WRAPPER_BASE_ADDRESS +
> > +               CE_WRAPPER_INTERRUPT_SUMMARY_ADDRESS));
> >  }
> >
> >  /* Host software's Copy Engine configuration. */
>
> > diff --git a/drivers/net/wireless/ath/ath10k/snoc.h b/drivers/net/wireless/ath/ath10k/snoc.h
> > index a3dd06f6ac62..5095d1893681 100644
> > --- a/drivers/net/wireless/ath/ath10k/snoc.h
> > +++ b/drivers/net/wireless/ath/ath10k/snoc.h
> > @@ -78,6 +78,7 @@ struct ath10k_snoc {
> >         unsigned long flags;
> >         bool xo_cal_supported;
> >         u32 xo_cal_data;
> > +       DECLARE_BITMAP(pending_ce_irqs, CE_COUNT_MAX);
>
> Do you need to clear this map if the interface goes down or if there's
> a firmware crash? Right now, I don't think there's a guarantee that
> we'll run through a NAPI poll in those cases, which is the only place
> you clear the map, and if the hardware/firmware has been reset, the
> state map is probably not valid.

Seems like a good idea.  Is the right place at the start of
ath10k_snoc_hif_start()?


> Otherwise, looks OK to me:
>
> Reviewed-by: Brian Norris <briannorris@...omium.org>

Thanks for the review!

-Doug