From: Brian Norris <briannorris@chromium.org>
To: "Jonas Dreßler" <verdre@v0yd.nl>
Cc: "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@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 12:40:58 -0700 [thread overview]
Message-ID: <CA+ASDXPKZ0i5Bi11Q=qqppY8OCgw=7m0dnPn0s+y+GAvvQodog@mail.gmail.com> (raw)
In-Reply-To: <20210830123704.221494-2-verdre@v0yd.nl>
On Mon, Aug 30, 2021 at 5:37 AM Jonas Dreßler <verdre@v0yd.nl> wrote:
>
> On the 88W8897 card it's very important the TX ring write pointer is
> updated correctly to its new value before setting the TX ready
> interrupt, otherwise the firmware appears to crash (probably because
> it's trying to DMA-read from the wrong place).
>
> Since PCI uses "posted writes" when writing to a register, it's not
> guaranteed that a write will happen immediately. That means the pointer
> might be outdated when setting the TX ready interrupt, leading to
> firmware crashes especially when ASPM L1 and L1 substates are enabled
> (because of the higher link latency, the write will probably take
> longer).
>
> So fix those firmware crashes by always forcing non-posted writes. We do
> that by simply reading back the register after writing it, just as a lot
> of other drivers do.
>
> There are two reproducers that are fixed with this patch:
>
> 1) During rx/tx traffic and with ASPM L1 substates enabled (the enabled
> substates are platform dependent), the firmware crashes and eventually a
> command timeout appears in the logs. That crash is fixed by using a
> non-posted write in mwifiex_pcie_send_data().
>
> 2) When sending lots of commands to the card, waking it up from sleep in
> very quick intervals, the firmware eventually crashes. That crash
> appears to be fixed by some other non-posted write included here.
>
> Signed-off-by: Jonas Dreßler <verdre@v0yd.nl>
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.
Brian
next prev parent reply other threads:[~2021-09-01 19:41 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 [this message]
2021-09-01 20:40 ` Andy Shevchenko
2021-09-01 21:04 ` Brian Norris
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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