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List:       linux-wireless
Subject:    Re: [PATCH] iwlwifi: mvm: check time event is over before disconnecting
From:       Filip Ayazi <filipayazi () gmail ! com>
Date:       2015-02-28 20:46:38
Message-ID: 54F2292E.5000803 () gmail ! com
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On 02/28/2015 08:55 PM, Emmanuel Grumbach wrote:
> On Sat, Feb 28, 2015 at 1:10 AM, Filip Ayazi <filipayazi@gmail.com> wrote:
> > On the 7260 time event was often ended before end_time and connections failed
> > with "No association and the time event is over already...".
> > This checks that the time event is actually over before disconnecting.
> > 
> > Signed-off-by: Filip Ayazi <filipayazi@gmail.com>
> While this patch is wrong I'd like to know if it helps.
It helped here (7260 on Lenovo E440).
I get a TE with unknown action message and successful connection now,
used to be TE ended with current time < end time and a disconnect,
even on networks with excellent signal strength. It used to happen
about 30% of the time with no apparent pattern, sometimes restarting
the interface fixed the issue.
> The patch is wrong because even if the driver thinks the time event
> should still be running, if the firmware indicates it has already
> ended, we should still disconnect. The reason for the disconnection is
> that we can't be sure that the firmware will have the proper timing
> for the beacon and hence for the DTIM. Both are critical to get a
> decent behavior while saving power.
You are right, few hours ago, after waking from suspend, I could not switch
the interface on (ifconfig said SIOCSIFFLAGS: Input/output error), reloading
iwlmvm module helped, so this was likely the cause.
> In any case, I doubt this patch does actually something because the
> firmware and the driver should really be close in their timings. If
> they aren't, it is fundamental bug in the firmware. While the firmware
> does have bugs just like any piece of software, I doubt it has such
> big ones :)
I do not see any other explanation apart from faulty hardware,
which doesn't seem likely :)
> 
> > ---
> > drivers/net/wireless/iwlwifi/mvm/time-event.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/wireless/iwlwifi/mvm/time-event.c \
> > b/drivers/net/wireless/iwlwifi/mvm/time-event.c index 54fafbf..b0aa892 100644
> > --- a/drivers/net/wireless/iwlwifi/mvm/time-event.c
> > +++ b/drivers/net/wireless/iwlwifi/mvm/time-event.c
> > @@ -256,7 +256,8 @@ static void iwl_mvm_te_handle_notif(struct iwl_mvm *mvm,
> > }
> > }
> > 
> > -       if (le32_to_cpu(notif->action) & TE_V2_NOTIF_HOST_EVENT_END) {
> > +       if (le32_to_cpu(notif->action) & TE_V2_NOTIF_HOST_EVENT_END &&
> > +           time_after(jiffies, te_data->end_jiffies)) {
> > IWL_DEBUG_TE(mvm,
> > "TE ended - current time %lu, estimated end %lu\n",
> > jiffies, te_data->end_jiffies);
> > --
> > 1.9.1
> > 
> > --
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