netdev - Re: [PATCH 1/2] ath10k: search for default BDF name provided in DT

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Date:   Tue, 19 Apr 2022 17:43:02 -0700
From:   Abhishek Kumar <kuabhs@...omium.org>
To:     Kalle Valo <kvalo@...nel.org>
Cc:     Doug Anderson <dianders@...omium.org>,
        Rakesh Pillai <pillair@...eaurora.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        ath10k <ath10k@...ts.infradead.org>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH 1/2] ath10k: search for default BDF name provided in DT

On Tue, Apr 12, 2022 at 3:47 AM Kalle Valo <kvalo@...nel.org> wrote:
>
> Abhishek Kumar <kuabhs@...omium.org> writes:
>
> > Hi All,
> >
> > Apologies for the late reply, too many things at the same time.
>
> Trust me, I know the feeling :)
>
> > Just a quick note, Qcomm provided a new BDF file with support for
> > 'bus=snoc,qmi-board-id=ff' as well, so even without this patch, the
> > non-programmed devices(with board-id=0xff) would work. However, for
> > optimization of the BDF search strategy, the above mentioned strategy
> > would still not work: - The stripping of full Board name would not
> > work if board-id itself is not programmed i.e. =0xff e.g. for
> > 'bus=snoc,qmi-board-id=ff,qmi-chip-id=320,variant=GO_LAZOR' => no
> > match 'bus=snoc,qmi-board-id=ff,qmi-chip-id=320' => no match
> > 'bus=snoc,qmi-board-id=ff' => no match 'bus=snoc' => no match because
> > all the BDFs contains board-id=67
>
> Sorry, not fully following your here. Are you saying that the problem is
> that WCN3990/hw1.0/board-2.bin is missing board file for 'bus=snoc'?
Ya, that is what I meant here, the board-2.bin file does not contain
an entry for 'bus=snoc' and so if board-id=oxff then still there
cannot be any BDF that matches. So adding BDF for 'bus=snoc' would
simplify the approach.
> That's easy to add, each board file within board-2.bin has multiple
> names so we can easily select one board file for which we add
> 'bus=snoc'.
>
> > So with this DT patch specifically for case 'bus=snoc,qmi-board-id=ff'
> > => no match, we fallback to default case ( the one provided in DT)
> > i.e. 'bus=snoc,qmi-board-id=67' => match . I do not see how exactly
> > the driver can know that it should check for a board-id of 67.
>
> Sorry, not following you here either. Why would the driver need to use
> board-id 67?
>
> > However, to still remove dependency on the DT, we can make the
> > board-id as no-op if it is not programmed i.e. if the board-id=ff then
> > we would pick any BDF that match 'bus=snoc,qmi-board-id=<XX>' where XX
> > can be any arbitrary number. Thoughts ?
>
> To me using just 'bus=snoc' is more logical than picking up an arbitrary
> number. But I might be missing something here.
The reason I mentioned that if the board-id=oxff then pick any
available BDF entry which matches
'bus=snoc,qmi-board-id=<XX>' is because:
- This will atleast let the wlan chip to boot.
- There is no BDF for 'bus=snoc' , so further stripping of boardname
will not find any match, but as you mentioned that BDF for 'bus=snoc'
can be added, then this will make the logic simpler and we don't have
to pick 'bus=snoc,qmi-board-id=<XX>' with any arbitrary board-id.
I will rollout a patch with this approach.
>
> --
> https://patchwork.kernel.org/project/linux-wireless/list/
>
> https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Thanks
Abhishek