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From: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
To: Johan Hovold <johan@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>,
	Support Opensource <support.opensource@diasemi.com>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>, linux-kernel@vger.kernel.org,
	Milo Kim <milo.kim@ti.com>,
	patches@opensource.wolfsonmicro.com,
	Fabio Estevam <fabio.estevam@freescale.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	stable <stable@vger.kernel.org>
Subject: Re: [PATCH 2/2] mfd: core: fix platform-device name collisions
Date: Wed, 25 Mar 2015 13:02:36 +0100
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Hi,

On Wednesday, March 25, 2015 12:07:05 PM Johan Hovold wrote:
> Since commit 6e3f62f0793e ("mfd: core: Fix platform-device id
> generation") we honour PLATFORM_DEVID_AUTO and PLATFORM_DEVID_NONE when
> registering mfd-devices.
> 
> Unfortunately, some mfd-drivers rely on the old behaviour of generating
> platform-device ids by adding the cell id also to the special value of
> PLATFORM_DEVID_NONE. The resulting platform ids are not only used to
> generate device-unique names, but are also used instead of the cell id
> to identify cells when probing subdevices.
> 
> These drivers should be updated to use PLATFORM_DEVID_AUTO, which would
> also allow more than one device to be registered without resorting to
> hacks (see for example wm831x), but lets fix the regression first by
> partially reverting the above mentioned commit with respect to
> PLATFORM_DEVID_NONE.
> 
> Fixes: 6e3f62f0793e ("mfd: core: Fix platform-device id generation")
> Cc: stable <stable@vger.kernel.org>	# v3.19
> Reported-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

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

> ---
>  drivers/mfd/mfd-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 2a87f69be53d..1aed3b7b8d9b 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -128,7 +128,7 @@ static int mfd_add_device(struct device *parent, int id,
>  	int platform_id;
>  	int r;
>  
> -	if (id < 0)
> +	if (id == PLATFORM_DEVID_AUTO)
>  		platform_id = id;
>  	else
>  		platform_id = id + cell->id;