From: "Jonas Dreßler" <verdre@v0yd.nl>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
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>,
"open list:TI WILINK WIRELES..." <linux-wireless@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
"Linux Kernel Mailing List" <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 16:01:54 +0200 [thread overview]
Message-ID: <7e38931e-2f1c-066e-088e-b27b56c1245c@v0yd.nl> (raw)
In-Reply-To: <CAHp75VeAKs=nFw4E20etKc3C_Cszyz9AqN=mLsum7F-BdVK5Rg@mail.gmail.com>
On 8/30/21 2:49 PM, Andy Shevchenko wrote:
> On Mon, Aug 30, 2021 at 3:38 PM 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 might be outdated when setting the TX ready interrupt, leading to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.
>
> Thanks for all this work!
>
> Nevertheless, do we have any commits that may be a good candidate to
> be in the Fixes tag here?
>
I don't think there's any commit we could point to, given that the bug
is probably somewhere in the firmware code.
>> Signed-off-by: Jonas Dreßler <verdre@v0yd.nl>
>> ---
>> drivers/net/wireless/marvell/mwifiex/pcie.c | 6 ++++++
>> 1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/net/wireless/marvell/mwifiex/pcie.c
b/drivers/net/wireless/marvell/mwifiex/pcie.c
>> index c6ccce426b49..bfd6e135ed99 100644
>> --- a/drivers/net/wireless/marvell/mwifiex/pcie.c
>> +++ b/drivers/net/wireless/marvell/mwifiex/pcie.c
>> @@ -237,6 +237,12 @@ static int mwifiex_write_reg(struct
mwifiex_adapter *adapter, int reg, u32 data)
>>
>> iowrite32(data, card->pci_mmap1 + reg);
>>
>> + /* Do a read-back, which makes the write non-posted,
ensuring the
>> + * completion before returning.
>
>> + * The firmware of the 88W8897 card is buggy and this avoids
crashes.
>
> Any firmware version reference? Would be nice to have just for the
> sake of record.
>
Pretty sure the crash is present in every firmware that has been
released, I've tried most of them. FTR, the current firmware version is
15.68.19.p21.
>> + */
>> + ioread32(card->pci_mmap1 + reg);
>> +
>> return 0;
>> }
>
>
next prev parent reply other threads:[~2021-09-01 14:02 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 [this message]
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
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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