Re: [PATCH] mmc: core: Do not pre-claim host in suspend

[Ulf Hansson <ulf.hansson@stericsson.com>]

On 04/19/2012 05:48 PM, Daniel Drake wrote:
> On Thu, Apr 19, 2012 at 4:02 AM, Vitaly Wool<vitalywool@gmail.com>  wrote:
>> I think it looks like a hack. Can you provide a better description of
>> where this deadlock actually happens?
>>
>> If libertas_sdio claims host as a part of its suspend operation from a
>> context different from the suspend context, isn't it libertas_sdio
>> that has to be fixed?
>
> libertas_sdio performs work in a workqueue during the suspend routine.
> It doesn't take long, but it is essential.
>
> Technically it would be possible to do the same work from the suspend
> thread without changing context. However, implementation-wise this is
> quite difficult. We cannot simply blast commands off to the card
> directly, we have to obey various rules and keep things in sync. This
> is done with an abstraction layer in the driver which is also shared
> with equivalent devices that connect over USB, SPI, etc. Sometimes we
> send commands from atomic context, or asynchronously, so thats why we
> do things in a workqueue.
>
> Breaking this abstraction for the suspend corner-case would be a pain,
> and I don't agree with the strange requirement that SDIO drivers can't
> communicate from other contexts in the suspend routine. My thoughts
> are here: http://article.gmane.org/gmane.linux.kernel.mmc/13899
>
> Ulf, you have understood the problem correctly and your patch solves
> the issue. Thanks for the fast response.
>
> Daniel

Thanks Daniel for testing, could we add your "Tested-by" to this patch then?

Myself, would like to do some more testing for MMC/SD, before adding 
mine Tested-by tag... get back to this soon..

Kind regards
Uffe