netdev - Re: [PATCH] ath10k: Wait until copy complete is actually done before completing

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Date:   Mon, 15 Jun 2020 08:02:00 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Kalle Valo <kvalo@...eaurora.org>
Cc:     Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, ath10k@...ts.infradead.org,
        Rakesh Pillai <pillair@...eaurora.org>,
        netdev <netdev@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>, kuabhs@...gle.com
Subject: Re: [PATCH] ath10k: Wait until copy complete is actually done before completing

Hi,

On Mon, Jun 15, 2020 at 7:56 AM Kalle Valo <kvalo@...eaurora.org> wrote:
>
> Doug Anderson <dianders@...omium.org> writes:
>
> > On Mon, Jun 15, 2020 at 7:32 AM Kalle Valo <kvalo@...eaurora.org> wrote:
> >>
> >> Douglas Anderson <dianders@...omium.org> wrote:
> >>
> >> > On wcn3990 we have "per_ce_irq = true".  That makes the
> >> > ath10k_ce_interrupt_summary() function always return 0xfff. The
> >> > ath10k_ce_per_engine_service_any() function will see this and think
> >> > that _all_ copy engines have an interrupt.  Without checking, the
> >> > ath10k_ce_per_engine_service() assumes that if it's called that the
> >> > "copy complete" (cc) interrupt fired.  This combination seems bad.
> >> >
> >> > Let's add a check to make sure that the "copy complete" interrupt
> >> > actually fired in ath10k_ce_per_engine_service().
> >> >
> >> > This might fix a hard-to-reproduce failure where it appears that the
> >> > copy complete handlers run before the copy is really complete.
> >> > Specifically a symptom was that we were seeing this on a Qualcomm
> >> > sc7180 board:
> >> >   arm-smmu 15000000.iommu: Unhandled context fault:
> >> >   fsr=0x402, iova=0x7fdd45780, fsynr=0x30003, cbfrsynra=0xc1, cb=10
> >> >
> >> > Even on platforms that don't have wcn3990 this still seems like it
> >> > would be a sane thing to do.  Specifically the current IRQ handler
> >> > comments indicate that there might be other misc interrupt sources
> >> > firing that need to be cleared.  If one of those sources was the one
> >> > that caused the IRQ handler to be called it would also be important to
> >> > double-check that the interrupt we cared about actually fired.
> >> >
> >> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> >> > Signed-off-by: Kalle Valo <kvalo@...eaurora.org>
> >>
> >> ath10k firmwares work very differently, on what hardware and firmware did you
> >> test this? I'll add that information to the commit log.
> >
> > I am running on a Qualcomm sc7180 SoC.
>
> Sorry, I was unclear, I meant the ath10k hardware :) I guess WCN3990 but
> what firmware version?

Ah, sorry!  Yes, it appears to be wcn3990 based on my device tree:

$ git grep -A2 wifi -- arch/arm64/boot/dts/qcom/sc7180.dtsi

wifi: wifi@...00000 {
        compatible = "qcom,wcn3990-wifi";
        reg = <0 0x18800000 0 0x800000>;
        reg-names = "membase";

Firmware isn't final yet, but currently my boot log shows:

qmi fw_version 0x322a01ea
fw_build_timestamp 2020-05-20 03:47
QC_IMAGE_VERSION_STRING=WLAN.HL.3.2.2-00490-QCAHLSWMTPL-1

-Doug