linux-kernel - Re: [PATCH] mmc: Test bus-width for old MMC devices (v2)

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Date:	Thu, 16 Dec 2010 23:40:32 +0000
From:	Chris Ball <cjb@...top.org>
To:	Takashi Iwai <tiwai@...e.de>
Cc:	Philip Rakity <prakity@...vell.com>,
	Aries Lee <arieslee@...cron.com>,
	zhangfei gao <zhangfei.gao@...il.com>, wuqm@...vell.com,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: Test bus-width for old MMC devices (v2)

Hi Takashi,

On Wed, Dec 15, 2010 at 08:14:24AM +0100, Takashi Iwai wrote:
> From: Aries Lee <arieslee@...cron.com>
> 
> Some old MMC devices fail with the 4/8 bits the driver tries to use
> exclusively.  This patch adds a test for the given bus setup and falls
> back to the lower bit mode (until 1-bit mode) when the test fails.
> 
> [Major rework and refactoring by tiwai]
> [Quirk addition and many fixes by prakity]
> 
> v1->v2:
>  - Rebased to the code with DDR support, set DDR bit properly
>  - Return always error when bus-switching fallback failed
>  - Define MMC_BUS_TEST_{R|W} in linux/mmc/mmc.h
>  - Add quirk MMC_CAP_BUS_WIDTH_TEST -- default not used for compatibility
>  - Ignore errors on BUS_TEST_W -- improves chances test will work
> 
> Signed-off-by: Aries Lee <arieslee@...cron.com>
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> Signed-off-by: Philip Rakity <prakity@...vell.com>
> Tested-by: Philip Rakity <prakity@...vell.com>

This looks good, but adds a warning:

drivers/mmc/core/mmc.c: In function ‘mmc_init_card’:
drivers/mmc/core/mmc.c:547: warning: ‘bus_width’ may be used uninitialized in this function

Thanks,

-- 
Chris Ball   <cjb@...top.org>   <http://printf.net/>
One Laptop Per Child
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