netdev - Re: [PATCH v2 1/2] ath10k: Keep track of which interrupts fired, don't poll them

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Message-Id: <20200826145011.C4E48C43387@smtp.codeaurora.org>
Date:   Wed, 26 Aug 2020 14:50:11 +0000 (UTC)
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Douglas Anderson <dianders@...omium.org>
Cc:     ath10k@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        briannorris@...omium.org, saiprakash.ranjan@...eaurora.org,
        linux-wireless@...r.kernel.org, pillair@...eaurora.org,
        kuabhs@...gle.com, Douglas Anderson <dianders@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v2 1/2] ath10k: Keep track of which interrupts fired,
 don't poll them

Douglas Anderson <dianders@...omium.org> wrote:

> If we have a per CE (Copy Engine) IRQ then we have no summary
> register.  Right now the code generates a summary register by
> iterating over all copy engines and seeing if they have an interrupt
> pending.
> 
> This has a problem.  Specifically if _none_ if the Copy Engines have
> an interrupt pending then they might go into low power mode and
> reading from their address space will cause a full system crash.  This
> was seen to happen when two interrupts went off at nearly the same
> time.  Both were handled by a single call of ath10k_snoc_napi_poll()
> but, because there were two interrupts handled and thus two calls to
> napi_schedule() there was still a second call to
> ath10k_snoc_napi_poll() which ran with no interrupts pending.
> 
> Instead of iterating over all the copy engines, let's just keep track
> of the IRQs that fire.  Then we can effectively generate our own
> summary without ever needing to read the Copy Engines.
> 
> Tested-on: WCN3990 SNOC WLAN.HL.3.2.2-00490-QCAHLSWMTPL-1
> 
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> Reviewed-by: Rakesh Pillai <pillair@...eaurora.org>
> Reviewed-by: Brian Norris <briannorris@...omium.org>
> Signed-off-by: Kalle Valo <kvalo@...eaurora.org>

My main concern of this patch is that there's no info how it works on other
hardware families. For example, QCA9984 is very different from WCN3990. The
best would be if someone can provide a Tested-on tags for other hardware (even
some of them).

https://wireless.wiki.kernel.org/en/users/drivers/ath10k/submittingpatches#hardware_families

-- 
https://patchwork.kernel.org/patch/11654625/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches