RE: [EXT] Re: [PATCH v2] wifi: mwifiex: avoid AP and STA running on different channel

[David Lin]

> From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> Sent: Tuesday, September 10, 2024 4:00 PM
> To: David Lin <yu-hao.lin@xxxxxxx>
> Cc: linux-wireless@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> briannorris@xxxxxxxxxxxx; kvalo@xxxxxxxxxx; francesco@xxxxxxxxxx; Pete
> Hsieh <tsung-hsien.hsieh@xxxxxxx>
> Subject: Re: [EXT] Re: [PATCH v2] wifi: mwifiex: avoid AP and STA running on
> different channel
> 
> Caution: This is an external email. Please take care when clicking links or
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> 
> On Tue, Sep 10, 2024 at 01:52:02AM +0000, David Lin wrote:
> > > From: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> > > Sent: Tuesday, September 10, 2024 5:05 AM
> > > To: David Lin <yu-hao.lin@xxxxxxx>
> > > Cc: linux-wireless@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > > briannorris@xxxxxxxxxxxx; kvalo@xxxxxxxxxx; francesco@xxxxxxxxxx;
> > > Pete Hsieh <tsung-hsien.hsieh@xxxxxxx>
> > > Subject: [EXT] Re: [PATCH v2] wifi: mwifiex: avoid AP and STA
> > > running on different channel
> > >
> > > Caution: This is an external email. Please take care when clicking
> > > links or opening attachments. When in doubt, report the message
> > > using the 'Report this email' button
> > >
> > >
> > > On Mon, Sep 02, 2024 at 04:43:11PM +0800, David Lin wrote:
> > > > Current firmware doesn't support AP and STA running on different
> > > > channels simultaneously.
> > > > FW crash would occur in such case.
> > > > This patch avoids the issue by disabling AP and STA to run on
> > > > different channels.
> > > >
> > > > Signed-off-by: David Lin <yu-hao.lin@xxxxxxx>
> > > > ---
> > > >
> > > > v2:
> > > >    - clean up code.
> > > >
> > > > ---
> > > >  .../net/wireless/marvell/mwifiex/cfg80211.c   | 17 ++++---
> > > >  drivers/net/wireless/marvell/mwifiex/util.c   | 44
> +++++++++++++++++++
> > > >  drivers/net/wireless/marvell/mwifiex/util.h   | 13 ++++++
> > > >  3 files changed, 69 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> > > > b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> > > > index 722ead51e912..3dbcab463445 100644
> > > > --- a/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> > > > +++ b/drivers/net/wireless/marvell/mwifiex/cfg80211.c
> > > > @@ -781,11 +781,9 @@ mwifiex_cfg80211_set_wiphy_params(struct
> > > > wiphy
> > > *wiphy, u32 changed)
> > > >               break;
> > > >
> > > >       case MWIFIEX_BSS_ROLE_STA:
> > > > -             if (priv->media_connected) {
> > > > -                     mwifiex_dbg(adapter, ERROR,
> > > > -                                 "cannot change wiphy params
> > > when connected");
> > > > -                     return -EINVAL;
> > > > -             }
> > > > +             if (priv->media_connected)
> > > > +                     break;
> > >
> > > This hunk seems unrelated to this patch. If this is needed then it
> > > deserves an extra patch along with an explanation why this is necessary.
> > >
> > > Sascha
> > >
> >
> > Without this hunk, AP and STA can't run on the same channel if some
> > wiphy parameters are setting.
> 
> Ok, I now see where you are aiming at. Here's the problematic function:
> 
> > static int
> > mwifiex_cfg80211_set_wiphy_params(struct wiphy *wiphy, u32 changed) {
> >       ...
> >
> >       priv = mwifiex_get_priv(adapter, MWIFIEX_BSS_ROLE_ANY);
> >
> >       switch (priv->bss_role) {
> >       case MWIFIEX_BSS_ROLE_UAP:
> >               if (priv->bss_started) {
> >                       mwifiex_dbg(adapter, ERROR,
> >                                   "cannot change wiphy params
> when bss started");
> >                       return -EINVAL;
> >               }
> >
> >               ...
> >               mwifiex_send_cmd(priv,
> HostCmd_CMD_UAP_SYS_CONFIG, ...);
> >
> >               break;
> >       case MWIFIEX_BSS_ROLE_STA:
> >               if (priv->media_connected) {
> >                       mwifiex_dbg(adapter, ERROR,
> >                                   "cannot change wiphy params
> when connected");
> >                       return -EINVAL;
> >               }
> >
> >               ...
> >               mwifiex_send_cmd(priv,
> HostCmd_CMD_802_11_SNMP_MIB,
> > ...);
> >
> >               break;
> >       }
> >
> >       return 0;
> > }
> 
> This function is for setting wiphy params like rts_threshold and others.
> 
> mwifiex_get_priv(adapter, MWIFIEX_BSS_ROLE_ANY) returns the first priv
> which by default is in station mode. Now if you start priv0 in station mode,
> then afterwards start priv1 in AP mode *and* have rts_threshold = xy in your
> config, then you run into the "cannot change wiphy params when connected"
> case.
> 
> I really wonder if the settings done in this function are per priv or per adapter.
> Is there one rts_threshold setting in a mwifiex chip or are there multiple (per
> vif/priv)?
> 
> If it's a global setting, then why are we interested in the media_connected
> state of one specific priv? Shouldn't we check all privs?
> 
> If it's a setting per priv, then why do we choose the same priv everytime in this
> function?
> 
> Either way, this function looks fishy and changing it should be done with an
> explanation, just dropping the error message and returning success is not
> enough.
> 
> Sascha
> 
> --

O.K. I will add comment in patch v3.

David