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From: Brian Norris <briannorris@chromium.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "Jonas Dreßler" <verdre@v0yd.nl>,
	"Amitkumar Karwar" <amitkarwar@gmail.com>,
	"Ganapathi Bhat" <ganapathi017@gmail.com>,
	"Xinming Hu" <huxinming820@gmail.com>,
	"Kalle Valo" <kvalo@codeaurora.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Tsuchiya Yuto" <kitakar@gmail.com>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	"<netdev@vger.kernel.org>" <netdev@vger.kernel.org>,
	"Linux Kernel" <linux-kernel@vger.kernel.org>,
	linux-pci <linux-pci@vger.kernel.org>,
	"Maximilian Luz" <luzmaximilian@gmail.com>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"Pali Rohár" <pali@kernel.org>
Subject: Re: [PATCH 1/2] mwifiex: Use non-posted PCI register writes
Date: Wed, 1 Sep 2021 14:04:04 -0700	[thread overview]
Message-ID: <CA+ASDXNGR2=sQ+w1LkMiY_UCfaYgQ5tcu2pbBn46R2asv83sSQ@mail.gmail.com> (raw)
In-Reply-To: <CAHp75VdR4VC+Ojy9NjAtewAaPAgowq-3rffrr3uAdOeiN8gN-A@mail.gmail.com>

On Wed, Sep 1, 2021 at 1:41 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Wed, Sep 1, 2021 at 11:25 PM Brian Norris <briannorris@chromium.org> wrote:
> > On Mon, Aug 30, 2021 at 5:37 AM Jonas Dreßler <verdre@v0yd.nl> wrote:
>
> ...
>
> > This might be good for many cases, but please read this commit:
> >
> > https://git.kernel.org/linus/062e008a6e83e7c4da7df0a9c6aefdbc849e2bb3
> > mwifiex: pcie: use posted write to wake up firmware
> >
> > It's very much intentional that this is a posted write in some cases.
> >
> > Without ensuring this doesn't regress, NAK from me.
>
> Can you ensure that from Chrome / Google perspective, please?

I mean, the context link should be pretty obvious. But sure: with this patch:

(a) all my least-favorite audio issues to debug return (audio is
especially latency-sensitive on the Rockchip RK3399 systems I have)
(b) latency spikes to ~6ms:
# trace-cmd record -p function_graph -O funcgraph-abstime -l
mwifiex_pm_wakeup_card
# trace-cmd report
   kworker/u13:0-199   [003]   348.987306: funcgraph_entry:      #
6219.500 us |  mwifiex_pm_wakeup_card();
   kworker/u13:0-199   [003]   349.316312: funcgraph_entry:      #
6267.625 us |  mwifiex_pm_wakeup_card();
   kworker/u13:3-4057  [001]   352.238530: funcgraph_entry:      #
6184.250 us |  mwifiex_pm_wakeup_card();
   kworker/u13:0-199   [002]   356.626366: funcgraph_entry:      #
6553.166 us |  mwifiex_pm_wakeup_card();
   kworker/u13:3-4057  [002]   356.709389: funcgraph_entry:      #
6212.500 us |  mwifiex_pm_wakeup_card();
   kworker/u13:3-4057  [002]   356.847215: funcgraph_entry:      #
6230.292 us |  mwifiex_pm_wakeup_card();
   kworker/u13:3-4057  [000]   356.897576: funcgraph_entry:      #
6451.667 us |  mwifiex_pm_wakeup_card();
   kworker/u13:0-199   [004]   357.175025: funcgraph_entry:      #
6204.042 us |  mwifiex_pm_wakeup_card();

whereas it used to look more like:

   kworker/u13:1-173   [005]   212.230542: funcgraph_entry:
7.000 us   |  mwifiex_pm_wakeup_card();
   kworker/u13:3-1768  [005]   213.886063: funcgraph_entry:
9.334 us   |  mwifiex_pm_wakeup_card();
   kworker/u13:3-1768  [002]   214.473273: funcgraph_entry:      +
11.375 us  |  mwifiex_pm_wakeup_card();
   kworker/u13:3-1768  [005]   214.530705: funcgraph_entry:
5.542 us   |  mwifiex_pm_wakeup_card();
   kworker/u13:1-173   [002]   215.050168: funcgraph_entry:      +
13.125 us  |  mwifiex_pm_wakeup_card();
   kworker/u13:1-173   [002]   215.106492: funcgraph_entry:      +
11.959 us  |  mwifiex_pm_wakeup_card();
   kworker/u13:3-1768  [005]   215.484807: funcgraph_entry:
8.459 us   |  mwifiex_pm_wakeup_card();
   kworker/u13:1-173   [003]   215.515238: funcgraph_entry:      +
15.166 us  |  mwifiex_pm_wakeup_card();
   kworker/u13:3-1768  [001]   217.175691: funcgraph_entry:      +
11.083 us  |  mwifiex_pm_wakeup_card();

I think it would be enough to only modify mwifiex_pm_wakeup_card() to
retain the posted version, but I'm not sure how that fits in with the
rest of the author's work. I suppose I can give a later version a run
if needed.

Brian

  reply	other threads:[~2021-09-01 21:11 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 12:37 [PATCH 0/2] mwifiex: Work around firmware bugs on 88W8897 chip Jonas Dreßler
2021-08-30 12:37 ` [PATCH 1/2] mwifiex: Use non-posted PCI register writes Jonas Dreßler
2021-08-30 12:49   ` Andy Shevchenko
2021-09-01 14:01     ` Jonas Dreßler
2021-09-01 15:47       ` Andy Shevchenko
2021-09-01 15:51       ` Pali Rohár
2021-09-01 16:51         ` Heiner Kallweit
2021-09-01 17:07           ` Johannes Berg
2021-09-01 19:07             ` Heiner Kallweit
2021-09-01 22:41             ` Bjorn Helgaas
2021-09-02 14:05               ` Bjorn Helgaas
2021-09-01 19:40   ` Brian Norris
2021-09-01 20:40     ` Andy Shevchenko
2021-09-01 21:04       ` Brian Norris [this message]
2021-09-01 21:07         ` Brian Norris
2021-09-18  7:37           ` Jonas Dreßler
2021-09-20 17:48             ` Brian Norris
2021-09-22 12:50               ` Jonas Dreßler
2021-09-23 15:28                 ` Jonas Dreßler
2021-09-23 19:37                   ` Andy Shevchenko
2021-09-23 19:41                   ` Andy Shevchenko
2021-09-23 20:22                     ` Pali Rohár
2021-09-30 15:38                       ` Jonas Dreßler
2021-09-30 15:42                         ` Pali Rohár
2021-09-30 16:14                           ` Jonas Dreßler
2021-09-30 16:19                             ` Pali Rohár
2021-09-30 16:22                               ` Jonas Dreßler
2021-09-30 16:39                                 ` Pali Rohár
2021-08-30 12:37 ` [PATCH 2/2] mwifiex: Try waking the firmware until we get an interrupt Jonas Dreßler
2021-08-30 12:51   ` Andy Shevchenko
2021-08-30 12:55     ` Andy Shevchenko
2021-09-25 17:32 ` [PATCH 0/2] mwifiex: Work around firmware bugs on 88W8897 chip Pali Rohár

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