netdev - Re: [PATCH] ath10k: Introduce a devicetree quirk to skip host cap QMI requests

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Message-ID: <87sg8heeta.fsf@codeaurora.org>
Date:   Mon, 07 Dec 2020 18:55:29 +0200
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Amit Pundir <amit.pundir@...aro.org>,
        Rob Herring <robh@...nel.org>, dt <devicetree@...r.kernel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Jeffrey Hugo <jeffrey.l.hugo@...il.com>,
        netdev@...r.kernel.org, linux-wireless@...r.kernel.org,
        Konrad Dybcio <konradybcio@...il.com>,
        ath10k <ath10k@...ts.infradead.org>,
        David S Miller <davem@...emloft.net>,
        John Stultz <john.stultz@...aro.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Sumit Semwal <sumit.semwal@...aro.org>
Subject: Re: [PATCH] ath10k: Introduce a devicetree quirk to skip host cap QMI requests

Bjorn Andersson <bjorn.andersson@...aro.org> writes:

> On Tue 03 Nov 01:48 CST 2020, Amit Pundir wrote:
>
>> Hi Rob, Bjorn, Kalle,
>> 
>> On Thu, 29 Oct 2020 at 19:10, Bjorn Andersson
>> <bjorn.andersson@...aro.org> wrote:
>> >
>> > On Tue 29 Sep 14:08 CDT 2020, Rob Herring wrote:
>> >
>> > > On Fri, Sep 25, 2020 at 11:59:41PM +0530, Amit Pundir wrote:
>> > > > There are firmware versions which do not support host capability
>> > > > QMI request. We suspect either the host cap is not implemented or
>> > > > there may be firmware specific issues, but apparently there seem
>> > > > to be a generation of firmware that has this particular behavior.
>> > > >
>> > > > For example, firmware build on Xiaomi Poco F1 (sdm845) phone:
>> > > > "QC_IMAGE_VERSION_STRING=WLAN.HL.2.0.c3-00257-QCAHLSWMTPLZ-1"
>> > > >
>> > > > If we do not skip the host cap QMI request on Poco F1, then we
>> > > > get a QMI_ERR_MALFORMED_MSG_V01 error message in the
>> > > > ath10k_qmi_host_cap_send_sync(). But this error message is not
>> > > > fatal to the firmware nor to the ath10k driver and we can still
>> > > > bring up the WiFi services successfully if we just ignore it.
>> > > >
>> > > > Hence introducing this DeviceTree quirk to skip host capability
>> > > > QMI request for the firmware versions which do not support this
>> > > > feature.
>> > >
>> > > So if you change the WiFi firmware, you may force a DT change too. Those
>> > > are pretty independent things otherwise.
>> > >
>> >
>> > Yes and that's not good. But I looked at somehow derive this from
>> > firmware version numbers etc and it's not working out, so I'm out of
>> > ideas for alternatives.
>> >
>> > > Why can't you just always ignore this error? If you can't deal with this
>> > > entirely in the driver, then it should be part of the WiFi firmware so
>> > > it's always in sync.
>> > >
>> >
>> > Unfortunately the firmware versions I've hit this problem on has gone
>> > belly up when receiving this request, that's why I asked Amit to add a
>> > flag to skip it.
>> 
>> So what is next for this DT quirk?
>> 
>
> Rob, we still have this problem and we've not come up with any way to
> determine in runtime that we need to skip this part of the
> initialization.

This is firmware version specific, right? There's also enum
ath10k_fw_features which is embedded within firmware-N.bin, we could add
a new flag there. But that means that a correct firmware-N.bin is needed
for each firmware version, not sure if that would work out. Just
throwing out ideas here.

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