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From: "Pali Rohár" <pali@kernel.org>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: "Jonas Dreßler" <verdre@v0yd.nl>,
	"Brian Norris" <briannorris@chromium.org>,
	"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,
	"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>
Subject: Re: [PATCH 1/2] mwifiex: Use non-posted PCI register writes
Date: Thu, 23 Sep 2021 22:22:31 +0200	[thread overview]
Message-ID: <20210923202231.t2zjoejpxrbbe5hc@pali> (raw)
In-Reply-To: <CAHp75Vd5iCLELx8s+Zvcj8ufd2bN6CK26soDMkZyC1CwMO2Qeg@mail.gmail.com>

On Thursday 23 September 2021 22:41:30 Andy Shevchenko wrote:
> On Thu, Sep 23, 2021 at 6:28 PM Jonas Dreßler <verdre@v0yd.nl> wrote:
> > On 9/22/21 2:50 PM, Jonas Dreßler wrote:
> 
> ...
> 
> > - Just calling mwifiex_write_reg() once and then blocking until the card
> > wakes up using my delay-loop doesn't fix the issue, it's actually
> > writing multiple times that fixes the issue
> >
> > These observations sound a lot like writes (and even reads) are actually
> > being dropped, don't they?
> 
> It sounds like you're writing into a not ready (fully powered on) device.

This reminds me a discussion with Bjorn about CRS response returned
after firmware crash / reset when device is not ready yet:
https://lore.kernel.org/linux-pci/20210922164803.GA203171@bhelgaas/

Could not be this similar issue? You could check it via reading
PCI_VENDOR_ID register from config space. And if it is not valid value
then card is not really ready yet.

> To check this, try to put a busy loop for reading and check the value
> till it gets 0.
> 
> Something like
> 
>   unsigned int count = 1000;
> 
>   do {
>     if (mwifiex_read_reg(...) == 0)
>       break;
>   } while (--count);
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko

  reply	other threads:[~2021-09-23 20:22 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
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 [this message]
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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