[meta-freescale] [meta-fsl-arm/V2][PATCH 1/2] linux-imx_3.14.28: fix initial MMC device detection

[Andreas Müller]

On Mon, Jun 8, 2015 at 6:29 PM, Gary Thomas <gary at mlbassoc.com> wrote:
> On 2015-06-08 10:19, Eric Nelson wrote:
>>
>> Hi Andreas,
>>
>> On 06/08/2015 05:48 AM, Andreas Müller wrote:
>>>
>>> On Variscite Varsom we have three devices connected to MMC
>>>
>>> * MMC1: eMMC
>>> * MMC2: SDCard
>>> * MMC3: Wifi
>>>
>>> Without this patch only the first device was detected properly.
>>> I found two workarounds which can be removed by this patch:
>>>
>>> 1. Variscite: booting from SDCard made possible by renumbering MMC
>>> devices [1].
>>> 2. BoundaryDevices: Add workqueues for each mmc_host [2]. This had been
>>> tested
>>>     here too but causes crashing sdcard for huge storage traffic.
>
>
> Can you (Andreas) elaborate on this?  Is there a procedure to show this
> failure?
> I'd like to test it on my board(s) that have multiple [active] MMC devices.
>
As this patch fixes some race there are likely many configurations
around working properly and it it not easy to say which configuration
causes reproducibility.
Interesting note regarding race: Before I found this patch I tried to
gather more information and enabled CONFIG_MMC_DEBUG and all MMC
devices were properly detected! So thought 'OK not the best solution
but a workaround fixing my problem'. Fortunately my colleague
complained next morning for massive spam in kernel log so I had to
look for a proper solution...

Andreas