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

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Message-ID: <1BAFE6F6C881BF42822005164F1491C33EA81214@DBDE01.ent.ti.com>
Date:	Thu, 13 Sep 2012 07:09:41 +0000
From:	"Hebbar, Gururaja" <gururaja.hebbar@...com>
To:	"S, Venkatraman" <svenkatr@...com>
CC:	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"cjb@...top.org" <cjb@...top.org>, "Nori, Sekhar" <nsekhar@...com>,
	"Rajashekhara, Sudhakar" <sudhakar.raj@...com>,
	"Bedia, Vaibhav" <vaibhav.bedia@...com>
Subject: RE: [PATCH] mmc: omap_hsmmc: Pass on the suspend failure to the PM
 core

On Tue, Sep 11, 2012 at 11:13:26, S, Venkatraman wrote:
> On Tue, Sep 4, 2012 at 6:38 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.
> >
> > 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.
> >
> 
> The last time we discussed this, didn't we plan to fix this differently ?
> Holding the return code of mmc_suspend_host in a separate variable and
> passing it to the caller
> of omap_hsmmc_suspend looks more sane to me.

I just pushed a new revision (V2) with above changes. I also added extra information 
(explanation with code snippet). Kindly let me know your review for the same.

> 

Regards, 
Gururaja
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