linux-kernel - Re: [Regression] Changes to i2c-piix4.c initialisation prevent loading of sp5100

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Date:   Sat, 1 Apr 2017 12:13:08 +0200
From:   Boszormenyi Zoltan <zboszor@...hu>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Paul Menzel <paulepanter@...rs.sourceforge.net>,
        Wolfram Sang <wsa@...-dreams.de>,
        Christian Fetzer <fetzer.ch@...il.com>,
        Jean Delvare <jdelvare@...e.com>, linux-i2c@...r.kernel.org,
        linux-watchdog@...r.kernel.org, 853122@...s.debian.org,
        Wim Van Sebroeck <wim@...ana.be>,
        Tim Small <tim@...ss.co.uk>,
        Nehal Shah <nehal-bakulchandra.shah@....com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Thomas Brandon <tbrandonau@...il.com>,
        Eddi De Pieri <eddi@...ieri.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [Regression] Changes to i2c-piix4.c initialisation prevent
 loading of sp5100_tco watchdog driver on AMD SB800 chipset

2017-03-31 17:05 keltezéssel, Guenter Roeck írta:
> On Fri, Mar 31, 2017 at 04:46:02PM +0200, Boszormenyi Zoltan wrote:
>> 2017-03-31 14:49 keltezéssel, Guenter Roeck írta:
>>> request_muxed_region() can fail, and literally every other driver
>>> using it checks for that failure. Please do the same.
>>
>> In what circumstances can request_muxed_region() fail? As far as
>> I can see, only if two drivers use the same I/O port base and the
>> already present region did not use IORESOURCE_MUXED which is
>> not the case here. When request_muxed_region() is used consistently,
>> subsequent requests are put on a wait queue and the first one is
>> woken up when the region is released. So, it's basically a mutex.
>> Am I missing something here?
>>
>
> Yes. failure to allocate the resource is one.

So, a common mutex should be used.

I have also added synchronization to the USB PCI quirks code and
have split the patch into three pieces now (USB quirks, i2c-piix4 and
sp5100_tco) and they were sent to the relevant mailing lists.

I don't know which subsystem wants to take it, all 3 patches are
needed at once.

Best regards,
Zoltán Böszörményi