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

[Amit Pundir]

On Wed, 30 Sep 2020 at 00:38, Rob Herring <robh at kernel.org> 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.

This is a valid concern and I'm not sure about the other devices, but
on PocoF1 I have tried all the three released firmware version updates:

WLAN.HL.2.0.c3-00257-QCAHLSWMTPLZ-1
WLAN.HL.2.0.c3-00445-QCAHLSWMTPLZ-1
WLAN.HL.2.0.c3-00534-QCAHLSWMTPLZ-1

and none of them works without this skip host-cap patch or equivalent
hack. PocoF1 is already 2+ years old device and sadly I do not expect
any major vendor update coming its way.

>
> 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.

I don't know the technical details of the ath10k/qmi driver, but I'm
OK if we just ignore the return value of
ath10k_qmi_host_cap_send_sync() and move along.

Regards,
Amit Pundir

>
> Rob