RE: wifi: rtw88: 8821CU hangs after some number of power-off/on cycles

[Ping-Ke Shih <pkshih@realtek.com>]

Marcin Ślusarz <marcin.slusarz@gmail.com> wrote:
> śr., 29 maj 2024 o 03:52 Ping-Ke Shih <pkshih@realtek.com> napisał(a):
> >
> > Marcin Ślusarz <marcin.slusarz@gmail.com> wrote:
> > > wt., 28 maj 2024 o 05:52 Ping-Ke Shih <pkshih@realtek.com> napisał(a):
> > > >
> > > > Marcin Ślusarz <marcin.slusarz@gmail.com> wrote:
> > > > >
> > > > > I found out that the reason for those hangs is a power-off+on sequence that's
> > > > > triggered by the above steps.
> > > >
> > > > To avoid power-off/on sequence once device becomes idle, I would like to add
> > > > a ips_disabled helper. Please revert your changes and apply my attached patch.
> > >
> > > My first attempt was very similar, and it fixed some cases but not all of them.
> > >
> > > This is due to the existence of a second source of power-offs - rtw_ops_stop,
> > > which is called, e.g., on downing the interface (ifconfig wlan0 down).
> >
> > Please try attached v2 patch. I would like to have an explicit helper
> > (i.e. always_power_on in v2) to have this fix, so days later people can be easy
> > to understand how it works. Not prefer adjusting existing flags to implicitly
> > have behavior you want.
> 
> So, do you think this is a chip issue, not just some driver misconfiguration?

I asked internal USB WiFi people who say vendor drivers of USB/SDIO can't
power-on/-off frequently but not very sure if hardware issue or driver issue.

> 
> I'm asking because if we are going in this direction, there's something
> more to fix... With your v2, very frequently, I hit WARN_ON(!local->started) in
> ieee80211_rx_napi (in wireless-next, the code was moved to ieee80211_rx_list).
> 
> With my patch, I checked and hit that WARN_ON, too, but very occasionally.
> 
> I think the difference is in what happens in rtw_ips_enter - I disabled only
> the power_off, but you also disabled everything else, including the cancelation
> of work_structs.
> 
> The warning itself sounds harmless, but I think users should never see such
> warnings, so this needs to be fixed somehow. Probably some additional
> work_struct(s) need to be canceled?
> 

I forgot to say my patch is compiled test only, and I didn't consider flow
too much, just to close the behavior of your patches. You can improve my patch
to be more reliable to avoid WARN_ON().  

Ping-Ke