netdev - Re: [PATCH 02/31] staging: wfx: do not send CAB while scanning

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Message-ID: <90855195.zGc3oIiVrW@pc-42>
Date:   Fri, 10 Sep 2021 19:12:55 +0200
From:   Jérôme Pouiller <jerome.pouiller@...abs.com>
To:     Kari Argillander <kari.argillander@...il.com>
Cc:     devel@...verdev.osuosl.org, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kalle Valo <kvalo@...eaurora.org>,
        "David S . Miller" <davem@...emloft.net>
Subject: Re: [PATCH 02/31] staging: wfx: do not send CAB while scanning

On Friday 10 September 2021 19:01:05 CEST Kari Argillander wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> 
> 
> On Fri, Sep 10, 2021 at 06:54:36PM +0200, Jérôme Pouiller wrote:
> > On Friday 10 September 2021 18:31:00 CEST Kari Argillander wrote:
> > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> > >
> > >
> > > On Fri, Sep 10, 2021 at 06:04:35PM +0200, Jerome Pouiller wrote:
> > > > From: Jérôme Pouiller <jerome.pouiller@...abs.com>
> > > >
> > > > During the scan requests, the Tx traffic is suspended. This lock is
> > > > shared by all the network interfaces. So, a scan request on one
> > > > interface will block the traffic on a second interface. This causes
> > > > trouble when the queued traffic contains CAB (Content After DTIM Beacon)
> > > > since this traffic cannot be delayed.
> > > >
> > > > It could be possible to make the lock local to each interface. But It
> > > > would only push the problem further. The device won't be able to send
> > > > the CAB before the end of the scan.
> > > >
> > > > So, this patch just ignore the DTIM indication when a scan is in
> > > > progress. The firmware will send another indication on the next DTIM and
> > > > this time the system will be able to send the traffic just behind the
> > > > beacon.
> > > >
> > > > The only drawback of this solution is that the stations connected to
> > > > the AP will wait for traffic after the DTIM for nothing. But since the
> > > > case is really rare it is not a big deal.
> > > >
> > > > Signed-off-by: Jérôme Pouiller <jerome.pouiller@...abs.com>
> > > > ---
> > > >  drivers/staging/wfx/sta.c | 10 ++++++++++
> > > >  1 file changed, 10 insertions(+)
> > > >
> > > > diff --git a/drivers/staging/wfx/sta.c b/drivers/staging/wfx/sta.c
> > > > index a236e5bb6914..d901588237a4 100644
> > > > --- a/drivers/staging/wfx/sta.c
> > > > +++ b/drivers/staging/wfx/sta.c
> > > > @@ -629,8 +629,18 @@ int wfx_set_tim(struct ieee80211_hw *hw, struct ieee80211_sta *sta, bool set)
> > > >
> > > >  void wfx_suspend_resume_mc(struct wfx_vif *wvif, enum sta_notify_cmd notify_cmd)
> > > >  {
> > > > +     struct wfx_vif *wvif_it;
> > > > +
> > > >       if (notify_cmd != STA_NOTIFY_AWAKE)
> > > >               return;
> > > > +
> > > > +     // Device won't be able to honor CAB if a scan is in progress on any
> > > > +     // interface. Prefer to skip this DTIM and wait for the next one.
> > >
> > > In one patch you drop // comments but you introduce some of your self.
> >
> > Indeed. When I wrote this patch, I didn't yet care to this issue. Is it
> > a big deal since it is fixed in patch 27?
> 
> No for me. Just little detail.

OK, right.


-- 
Jérôme Pouiller