linux-kernel - Re: [PATCH] ath10k: support bus and device specific API 1 BDF selection

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Message-ID: <09a27912-9ea4-fe75-df72-41ba0fa5fd4e@gmail.com>
Date:   Wed, 8 Dec 2021 15:07:24 +0100
From:   Christian Lamparter <chunkeey@...il.com>
To:     Robert Marko <robimarko@...il.com>, Kalle Valo <kvalo@...nel.org>
Cc:     kvalo@...eaurora.org, davem@...emloft.net, kuba@...nel.org,
        ath10k@...ts.infradead.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ath10k: support bus and device specific API 1 BDF
 selection

On 08/12/2021 13:21, Robert Marko wrote:
> On Tue, 7 Dec 2021 at 19:06, Kalle Valo <kvalo@...nel.org> wrote:
>>
>> Robert Marko <robimarko@...il.com> wrote:
>>
>>> Some ath10k IPQ40xx devices like the MikroTik hAP ac2 and ac3 require the
>>> BDF-s to be extracted from the device storage instead of shipping packaged
>>> API 2 BDF-s.
>>>
>>> This is required as MikroTik has started shipping boards that require BDF-s
>>> to be updated, as otherwise their WLAN performance really suffers.
>>> This is however impossible as the devices that require this are release
>>> under the same revision and its not possible to differentiate them from
>>> devices using the older BDF-s.
>>>
>>> In OpenWrt we are extracting the calibration data during runtime and we are
>>> able to extract the BDF-s in the same manner, however we cannot package the
>>> BDF-s to API 2 format on the fly and can only use API 1 to provide BDF-s on
>>> the fly.
>>> This is an issue as the ath10k driver explicitly looks only for the
>>> board.bin file and not for something like board-bus-device.bin like it does
>>> for pre-cal data.
>>> Due to this we have no way of providing correct BDF-s on the fly, so lets
>>> extend the ath10k driver to first look for BDF-s in the
>>> board-bus-device.bin format, for example: board-ahb-a800000.wifi.bin
>>> If that fails, look for the default board file name as defined previously.
>>>
>>> Signed-off-by: Robert Marko <robimarko@...il.com>
>>
>> Can someone review this, please? I understand the need for this, but the board
>> handling is getting quite complex in ath10k so I'm hesitant.
>>
>> What about QCA6390 and other devices. Will they still work?
> Hi Kalle,
> everything else should just continue working as before unless the
> board-bus-device.bin file
> exists it will just use the current method to fetch the BDF.
> 
> Also, this only applies to API1 BDF-s.
> 
> We are really needing this as currently there are devices with the
> wrong BDF being loaded as
> we have no way of knowing where MikroTik changed it and dynamic
> loading would resolve
> all of that since they are one of the rare vendors that embed the
> BDF-s next to calibration data.

Isn't the only user of this the non-upstreamable rb_hardconfig
mikrotik platform driver? So, in your case the devices in question
needs to setup a detour through the userspace firmware (helper+scripts)
to pull on the sysfs of that mikrotik platform driver? Wouldn't it
be possible to do this more directly?

Cheers,
Christian