linux-kernel - Re: [PATCH REGRESSION] Revert "ath10k: add quiet mode support for QCA6174/QCA9377"

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Date:   Thu, 8 Nov 2018 09:30:43 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     govinds@...eaurora.org
Cc:     rmanohar@...eaurora.org, ath10k@...ts.infradead.org,
        linux-wireless@...r.kernel.org,
        Linux Kernel <linux-kernel@...r.kernel.org>,
        yyuwang@...eaurora.org, pillair@...eaurora.org,
        stable <stable@...r.kernel.org>,
        linux-wireless-owner@...r.kernel.org
Subject: Re: [PATCH REGRESSION] Revert "ath10k: add quiet mode support for QCA6174/QCA9377"

On Wed, Nov 7, 2018 at 8:32 PM Govind Singh <govinds@...eaurora.org> wrote:
> On 2018-11-08 03:00, Rajkumar Manoharan wrote:
> > On 2018-11-07 10:56, Brian Norris wrote:
> >> This reverts commit cfb353c0dc058bc1619cc226d3cbbda1f360bdd3.
> >>
> >> WCN3990 firmware does not yet implement this feature, and so it
> >> crashes
> >> like this:
> >>
> >>   fatal error received: err_qdi.c:456:EX:wlan_process:1:WLAN
> >> RT:207a:PC=b001b4f0
> >>
> >> This feature can be re-implemented with a proper service bitmap or
> >> other
> >> feature-discovery mechanism in the future. But it should not break
> >> working boards.
> >>
> > Brian,
> >
> > The change "ath10k: add quiet mode support for QCA6174/QCA9377" was
> > merged even
> > before full WCN3990 device support was added in ath10k. How come it
> > could be regression
> > for WCN3990. I know both are sharing same WMI-TLV interface but
> > reverting this
> > will break QCA6174/QCA9377. no?

I don't see how the revert would "break" QCA6174 -- QCA6174 worked
just fine without this feature and should continue to do so.

> This regression is found while we switched from 4.18 + WCN3990
> back-ports to 4.19.

^^ What Govind said. WCN3990 support has been trickling in over a few
releases, and it doesn't seem kosher to allow people to submit
regressions in the midst of that.

> > I would prefer to handle this within WMI callback or upper layer.
> >
>
> IMO, we should use (WMI_SERVICE_THERMAL_MGMT | WMI_SERVICE_THERM_THROT )
> service bitmap check and call
> ath10k_thermal_set_throttling only if fw supports THERMAL THROTTLE
> feature. But we need to ensure all
> available ath10k fw's are reporting this service.

And the above notes from Govind highlight this -- if the feature was
not protected by the appropriate service flags, then we can't be sure
that you didn't break a bunch of other firmware releases out there.
Linux should not break for everyone just because you spun a firmware
release.

Of course, I'll leave it up to Kalle as to how he wants to mediate
this. And if you come up with a solid patch soon that can fix this
without dropping the feature, then so be it.

Brian