linux-kernel - Re: [PATCH V2] mmc: omap_hsmmc: Pass on the suspend failure to the PM core

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Message-ID: <m34nmuk1jx.fsf@pullcord.laptop.org>
Date:	Wed, 19 Sep 2012 01:46:10 -0400
From:	Chris Ball <cjb@...top.org>
To:	"S\, Venkatraman" <svenkatr@...com>
Cc:	"Hebbar\, Gururaja" <gururaja.hebbar@...com>,
	linux-omap@...r.kernel.org, linux-mmc@...r.kernel.org,
	rob.herring@...xeda.com, linux-kernel@...r.kernel.org,
	grant.likely@...retlab.ca, nsekhar@...com, sudhakar.raj@...com,
	Vaibhav Bedia <vaibhav.bedia@...com>
Subject: Re: [PATCH V2] mmc: omap_hsmmc: Pass on the suspend failure to the PM core

Hi,

On Mon, Sep 17 2012, S, Venkatraman wrote:
> On Thu, Sep 13, 2012 at 12:01 PM, Hebbar, Gururaja
> <gururaja.hebbar@...com> wrote:
>> From: Vaibhav Bedia <vaibhav.bedia@...com>
>>
>> In some cases mmc_suspend_host() is not able to claim the
>> host and proceed with the suspend process. The core returns
>> -EBUSY to the host controller driver. Unfortunately, the
>> host controller driver does not pass on this information
>> to the PM core and hence the system suspend process continues.
>>
>>         ret = mmc_suspend_host(host->mmc);
>>         if (ret) {
>>                 host->suspended = 0;
>>                 if (host->pdata->resume) {
>>                         ret = host->pdata->resume(dev, host->slot_id);
>>
>> The return status from mmc_suspend_host() is overwritten by return
>> status from host->pdata->resume. So the original return status is lost.
>>
>> In these cases the MMC core gets to an unexpected state
>> during resume and multiple issues related to MMC crop up.
>> 1. Host controller driver starts accessing the device registers
>> before the clocks are enabled which leads to a prefetch abort.
>> 2. A file copy thread which was launched before suspend gets
>> stuck due to the host not being reclaimed during resume.
>>
>> To avoid such problems pass on the -EBUSY status to the PM core
>> from the host controller driver. With this change, MMC core
>> suspend might still fail but it does not end up making the
>> system unusable. Suspend gets aborted and the user can try
>> suspending the system again.
>>
>> Signed-off-by: Vaibhav Bedia <vaibhav.bedia@...com>
>> Signed-off-by: Hebbar, Gururaja <gururaja.hebbar@...com>
>
> This version is good.
>
> Acked-by: Venkatraman S <svenkatr@...com>

Thanks, pushed to mmc-next for 3.7, with a stable@ tag added (right?).

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