From: Jean Delvare <jdelvare@suse.de>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Christian Fetzer <fetzer.ch@gmail.com>,
linux-i2c@vger.kernel.org,
Jarkko Nikula <jarkko.nikula@linux.intel.com>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Wolfram Sang <wsa@the-dreams.de>,
galandilias@gmail.com, Thomas Brandon <tbrandonau@gmail.com>,
Eddi De Pieri <eddi@depieri.net>
Subject: Re: [PATCH v3 4/5] i2c-piix4: Add support for multiplexed main adapter in SB800
Date: Fri, 22 Jan 2016 13:39:53 +0100 [thread overview]
Message-ID: <20160122133953.1945e36e@endymion.delvare> (raw)
In-Reply-To: <1447065942.31665.29.camel@linux.intel.com>
Sorry for the late reaction, but...
On Mon, 09 Nov 2015 12:45:42 +0200, Andy Shevchenko wrote:
> On Sat, 2015-11-07 at 12:35 +0100, Christian Fetzer wrote:
> (...)
> > @@ -129,10 +133,12 @@ static const struct dmi_system_id
> > piix4_dmi_ibm[] = {
> > };
> >
> > /* SB800 globals */
> > +DEFINE_MUTEX(piix4_mutex_sb800);
>
> Same question as for patch 3.
Noooooo!
The mutex is needed to ensure that only one of the 4 multiplexed SMBus
ports is used at any given time. i2c_piix4_adapdata is per i2c_adapter,
so if you move the mutex there you get one mutex per SMBus port, which
completely voids the point of having a mutex. A per-port mutex doesn't
protect anything, all it does is serialize the access to THAT port, but
i2c-core already takes care of this (thankfully.)
So moving this mutex to i2c_piix4_adapdata introduced a serious bug in
the driver, which needs to be fixed ASAP.
--
Jean Delvare
SUSE L3 Support
next prev parent reply other threads:[~2016-01-22 12:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-07 11:35 [PATCH v3 0/5] Support multiplexed main SMBus interface on SB800 Christian Fetzer
2015-11-07 11:35 ` [PATCH v3 1/5] i2c-piix4: Optionally release smba in piix4_adap_remove Christian Fetzer
2015-11-09 11:24 ` Mika Westerberg
2015-11-07 11:35 ` [PATCH v3 2/5] i2c-piix4: Convert piix4_main_adapter to array Christian Fetzer
2015-11-07 11:35 ` [PATCH v3 3/5] i2c-piix4: Request base address index region once for SB800 Christian Fetzer
2015-11-09 10:40 ` Andy Shevchenko
2015-11-07 11:35 ` [PATCH v3 4/5] i2c-piix4: Add support for multiplexed main adapter in SB800 Christian Fetzer
2015-11-09 10:45 ` Andy Shevchenko
2016-01-22 12:39 ` Jean Delvare [this message]
2016-01-22 13:20 ` Andy Shevchenko
2015-11-07 11:35 ` [PATCH v3 5/5] i2c-piix4: Add adapter port name support for SB800 chipset Christian Fetzer
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