linux-kernel - Re: [PATCH] MMC/omap_hsmmc: handle failure of regulator

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Message-ID: <20120730162414.3818bded@notabene.brown>
Date:	Mon, 30 Jul 2012 16:24:14 +1000
From:	NeilBrown <neilb@...e.de>
To:	Rajendra Nayak <rnayak@...com>
Cc:	Chris Ball <cjb@...top.org>, Venkatraman S <svenkatr@...com>,
	Balaji T K <balajitk@...com>, linux-omap@...r.kernel.org,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MMC/omap_hsmmc: handle failure of regulator_get better.

On Mon, 30 Jul 2012 10:50:36 +0530 Rajendra Nayak <rnayak@...com> wrote:

> On Monday 30 July 2012 05:42 AM, NeilBrown wrote:
> >
> > 1/ if regulator_get fails, return an error.  This is important
> >     if it failed with EPROBE_DEFER, as the probe needs to be
> >     deferred.
> >
> > 2/ Don't set .set_power until the regulator has been found, or
> >     the deferred probe will not bother calling omap_hsmmc_reg_get().
> 
> I am not very sure, but aren't the data structures re-allocated on a
> re-probe (after it was deferred) causing .set_power to be lost anyway?
> 

Apparently not - as I needed to make that change before the re-probe would
work.

Looking at the code to remind myself:

#define mmc_slot(host)		(host->pdata->slots[host->slot_id])

so the slot is inside the platform data which is allocated in
omap_hsmmc_init_one, called from omap_hsmmc_init.
This is all prior to the probing of the device.

So no: once set_power is set, it stays set.

Thanks,
NeilBrown

> >
> > Signed-off-by: NeilBrown<neilb@...e.de>
> >
> > diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
> > index 389a3ee..f052c29 100644
> > --- a/drivers/mmc/host/omap_hsmmc.c
> > +++ b/drivers/mmc/host/omap_hsmmc.c
> > @@ -299,12 +299,12 @@ static int omap_hsmmc_reg_get(struct omap_hsmmc_host *host)
> >   	struct regulator *reg;
> >   	int ocr_value = 0;
> >
> > -	mmc_slot(host).set_power = omap_hsmmc_set_power;
> > -
> >   	reg = regulator_get(host->dev, "vmmc");
> >   	if (IS_ERR(reg)) {
> >   		dev_dbg(host->dev, "vmmc regulator missing\n");
> > +		return PTR_ERR(reg);
> >   	} else {
> > +		mmc_slot(host).set_power = omap_hsmmc_set_power;
> >   		host->vcc = reg;
> >   		ocr_value = mmc_regulator_get_ocrmask(reg);
> >   		if (!mmc_slot(host).ocr_mask) {


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