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From:   Sean Wang <sean.wang@kernel.org>
Date:   Wed, 17 Aug 2022 01:28:37 -0700
Message-ID: <CAGp9LzrqYsXAPsbZvTy-_3Tnu23oc11KHdxNs9WvYfe0JHQaDg@mail.gmail.com>
Subject: Re: [PATCH 1/9] wifi: mac80211: allow enabling chanctx until hw registration
To:     Johannes Berg <johannes@sipsolutions.net>
Cc:     =?UTF-8?B?U2VhbiBXYW5nICjnjovlv5fkupgp?= <sean.wang@mediatek.com>,
        Felix Fietkau <nbd@nbd.name>, lorenzo.bianconi@redhat.com,
        Soul.Huang@mediatek.com, YN.Chen@mediatek.com,
        Leon.Yen@mediatek.com, Eric-SY.Chang@mediatek.com,
        Deren.Wu@mediatek.com, km.lin@mediatek.com,
        jenhao.yang@mediatek.com, robin.chiu@mediatek.com,
        Eddie.Chen@mediatek.com, ch.yeh@mediatek.com,
        posh.sun@mediatek.com, ted.huang@mediatek.com,
        Stella.Chang@mediatek.com, Tom.Chou@mediatek.com,
        steve.lee@mediatek.com, jsiuda@google.com, frankgor@google.com,
        kuabhs@google.com, druth@google.com, abhishekpandit@google.com,
        shawnku@google.com, linux-wireless@vger.kernel.org,
        linux-mediatek@lists.infradead.org
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Hi Johannes,

On Tue, Aug 16, 2022 at 3:22 AM Johannes Berg <johannes@sipsolutions.net> wrote:
>
> On Tue, 2022-08-16 at 08:03 +0800, sean.wang@mediatek.com wrote:
> > From: Sean Wang <sean.wang@mediatek.com>
> >
> > MT7921 device can be supported with the channel context depending on
> > the newer firmware so that we need a way to enable the chanctx related
> > methods until hw is being registered.
> >
> > Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> > ---
> >  net/mac80211/main.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/net/mac80211/main.c b/net/mac80211/main.c
> > index 5b1c47ed0cc0..98d05ed1a081 100644
> > --- a/net/mac80211/main.c
> > +++ b/net/mac80211/main.c
> > @@ -1011,6 +1011,14 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
> >               return -EINVAL;
> >  #endif
> >
> > +     /* check all or no channel context operations exist */
> > +     i = !!local->ops->add_chanctx + !!local->ops->remove_chanctx +
> > +         !!local->ops->change_chanctx + !!local->ops->assign_vif_chanctx +
> > +         !!local->ops->unassign_vif_chanctx;
> > +     if (WARN_ON(i != 0 && i != 5))
> > +             return -EINVAL;
> > +     local->use_chanctx = i == 5;
> > +
>
> Not sure I understand this - this just *adds* code, based on the
> description I would've expected you to *move* code?

It can be done and looks better by *move* code instead of *adds* code.
I will change it in the next version. Thanks for your input.

>
> In any case, I'm not sure I see how this makes sense - ops is supposed
> to be const, and you're supposed to pass it to alloc_hw already, so how
> would it change?!
>
> Also, conceptually, I'm not sure why it's needed to alloc_hw before
> loading firmware, we also have a lot of things depend on the firmware
> capabilities in iwlwifi/mvm, and so we alloc/register HW after loading
> firmware.
>

Based on mt76 driver logic, alloc_hw would be needed before loading firmware
because alloc_hw creates an instance of "struct mt76_dev*" the
firmware loading relies on,
and so the firmware capabilities cannot be decided before we alloc_hw
in mt76 driver.

    sean

> johannes
>