Re: [PATCH v2 0/5] mfd: Fix platform device ids to avoid probe failure

From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
To: Johan Hovold <johan@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Support Opensource <support.opensource@diasemi.com>,
	Milo Kim <milo.kim@ti.com>,
	patches@opensource.wolfsonmicro.com,
	Fabio Estevam <fabio.estevam@freescale.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 0/5] mfd: Fix platform device ids to avoid probe failure
Date: Wed, 25 Mar 2015 13:04:49 +0100	[thread overview]
Message-ID: <1690558.fFtM3q1TrB@amdc1032> (raw)
In-Reply-To: <20150325110231.GC10412@localhost>

Hi,

On Wednesday, March 25, 2015 12:02:31 PM Johan Hovold wrote:
> On Mon, Mar 23, 2015 at 02:11:50PM +0100, Bartlomiej Zolnierkiewicz wrote:
> > On Monday, March 23, 2015 11:07:18 AM Johan Hovold wrote:
> > > On Fri, Mar 20, 2015 at 08:23:18PM +0100, Bartlomiej Zolnierkiewicz wrote:
> > > 
> > > > Commit 6e3f62f0793e ("mfd: core: Fix platform-device id generation")
> > > > changed the way platform device ids are generated from mfd id base and
> > > > cell ids in mfd_add_device().  Unfortunately the change in question
> > > > breaks mfd drivers which are using mfd_add_devices() with mfd id base
> > > > equal to -1 and non-zero cell ids (used to distinguish cells with
> > > > the same name field).  The result is that mfd core tries to register
> > > > platform devices with the same name which obviously fails and leads
> > > > to mfd device probe failure.
> > > 
> > > First of all, thanks for finding these. I obviously overlooked this
> > > class of drivers when fixing the device-id generation.
> > > 
> > > > Changing mfd_add_devices() mfd id base from -1 to 0 and at the same
> > > > time setting proper cell ids for all cells fixes the issue.
> > > 
> > > This is however not the right fix. Instead you should be using
> > > PLATFORM_DEVID_AUTO and keep the non-zero cell-ids as is, as this will
> > > allow more than one mfd-device to be registered without resorting to
> > > hacks.
> > 
> > Conversion of a driver to use PLATFORM_DEVID_AUTO changes names of
> > all platform devices registered by the driver.  In my patchset I just
> > tried to restore the broken functionality (patch that broke it went
> > in v3.19).  I thought that it was the best solution for v3.19 and
> > v4.0-rc4 (then PLATFORM_DEVID_AUTO conversion can be done sometime
> > later, i.e. in v4.1).
> 
> I think you're right. We should do the conversion to PLATFORM_DEVID_AUTO
> later.
> 
> I'm responding to this mail with two patches for v4.0 fixing the da9052
> driver, which is currently broken although not in the way suggested by
> your v1-series, and the other drivers you identified by doing a partial
> revert of commit 6e3f62f0793e ("mfd: core: Fix platform-device id
> generation").

Both patches look good to me.  Thank you for fixing this.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics