Re: [PATCH RFC v2 0/4] wifi: ath10k: support board-specific firmware overrides

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On Wed, 6 Mar 2024 at 13:15, Kalle Valo <kvalo@kernel.org> wrote:
>
> Dmitry Baryshkov <dmitry.baryshkov@linaro.org> writes:
>
> > On Wed, 6 Mar 2024 at 11:04, Kalle Valo <kvalo@kernel.org> wrote:
> >
> >>
> >> Dmitry Baryshkov <dmitry.baryshkov@linaro.org> writes:
> >>
> >> > On WCN3990 platforms actual firmware, wlanmdsp.mbn, is sideloaded to the
> >> > modem DSP via the TQFTPserv. These MBN files are signed by the device
> >> > vendor, can only be used with the particular SoC or device.
> >> >
> >> > Unfortunately different firmware versions come with different features.
> >> > For example firmware for SDM845 doesn't use single-chan-info-per-channel
> >> > feature, while firmware for QRB2210 / QRB4210 requires that feature.
> >> >
> >> > Allow board DT files to override the subdir of the fw dir used to lookup
> >> > the firmware-N.bin file decribing corresponding WiFi firmware.
> >> > For example, adding firmware-name = "qrb4210" property will make the
> >> > driver look for the firmware-N.bin first in ath10k/WCN3990/hw1.0/qrb4210
> >> > directory and then fallback to the default ath10k/WCN3990/hw1.0 dir.
> >> >
> >> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> >> > ---
> >> > Changes in v2:
> >> > - Fixed the comment about the default board name being NULL (Kalle)
> >> > - Expanded commit message to provide examples for firmware paths (Kalle)
> >> > - Added a note regarding board-2.bin to the commit message (Kalle)
> >> > - Link to v1:
> >> > https://lore.kernel.org/r/20240130-wcn3990-firmware-path-v1-0-826b93202964@linaro.org
> >>
> >> From my point of view this looks good now but let's see what others say.
> >> Is there a specific reason why you marked this as RFC still?
> >
> > No, I just forgot to remove it from the series settings, so you can
> > consider it as final.
>
> Good, so let's ignore the RFC label for this v2.
>
> > I had one minor question in my head (but that's mostly for patches 3
> > and 4): in linux-firmware we will have ath10k/WCN3990/hw1.0/qcm2290
> > and make qrb4210 as a symlink to it. Is that fine from your POV?
>
> Yes, I think using a symlink is a good idea.
>
> > Or should we use sensible device names (e.g. qcom-rb1)?
>
> I guess 'qcom-rb1' refers to 'Qualcomm Robotics RB1' board? In other
> words, the question is that should we use chipset specific names like
> 'qcm2290' or product based names like 'qcom-rb1'?
>
> That's a good question for which I don't have a good answer :) I'm not
> very familiar with WCN3990 hardware and SoCs to have a full picture of
> all this, especially how the firmware images are signed or what
> different firmware branches there are etc.

I checked Pixel-3 data, it has wlanmdsp.mbn signed by Google.

>
> To be on the safe side using 'qcom-rb1' makes sense but on the other
> hand that means we need to update linux-firmware (basically add a new
> symlink) everytime a new product is added. But are there going to be
> that many new ath10k based products?
>
> Using 'qcm2290' is easier because for a new product then there only
> needs to be a change in DTS and no need to change anything
> linux-firmware. But here the risk is that if there's actually two
> different ath10k firmware branches for 'qcm2290'. If that ever happens
> (I hope not) I guess we could solve that by adding new 'qcm2290-foo'
> directory?
>
> But I don't really know, thoughts?

After some thought, I'd suggest to follow approach taken by the rest
of qcom firmware:
put a default (accepted by non-secured hardware) firmware to SoC dir
and then put a vendor-specific firmware into subdir. If any of such
vendors appear, we might even implement structural fallback: first
look into sdm845/Google/blueline, then in sdm845/Google, sdm845/ and
finally just under hw1.0.

>
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--
With best wishes
Dmitry