linux-kernel - Re: [PATCH] MMC: move regulator handling closer to core v3

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Message-Id: <20100908155114.880463fc.akpm@linux-foundation.org>
Date:	Wed, 8 Sep 2010 15:51:14 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Linus Walleij <linus.walleij@...ricsson.com>
Cc:	linux-kernel@...r.kernel.org, Liam Girdwood <lrg@...mlogic.co.uk>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Tony Lindgren <tony@...mide.com>,
	Adrian Hunter <adrian.hunter@...ia.com>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Sundar Iyer <sundar.iyer@...ricsson.com>,
	Daniel Mack <daniel@...aq.de>,
	Pierre Ossman <pierre@...man.eu>,
	Matt Fleming <matt@...sole-pimps.org>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Eric Miao <eric.y.miao@...il.com>,
	Cliff Brake <cbrake@...-systems.com>,
	Jarkko Lavinen <jarkko.lavinen@...ia.com>,
	linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] MMC: move regulator handling closer to core v3

On Sun,  5 Sep 2010 11:05:38 +0200
Linus Walleij <linus.walleij@...ricsson.com> wrote:

> After discovering a problem in regulator reference counting I
> took Mark Brown's advice to move the reference count into the
> MMC core by making the regulator status a member of
> struct mmc_host.
> 
>
> ...
>
> -static inline void pxamci_set_power(struct pxamci_host *host, unsigned int vdd)
> +static inline void pxamci_set_power(struct pxamci_host *host,
> +				    unsigned char power_mode,
> +				    unsigned int vdd)
>  {
>  	int on;
>  
> -#ifdef CONFIG_REGULATOR
> -	if (host->vcc)
> -		mmc_regulator_set_ocr(host->vcc, vdd);
> -#endif
> +	if (host->vcc) {
> +		int ret;
> +
> +		if (power_mode == MMC_POWER_UP)
> +			ret = mmc_regulator_set_ocr(host->mmc, host->vcc, vdd);
> +		else if (power_mode == MMC_POWER_OFF)
> +			ret = mmc_regulator_set_ocr(host->mmc, host->vcc, 0);
> +	}

There's no point in copying the return value into a local then ignoring
it.  mmc_regulator_set_ocr() can return a negative errno so we should
test for that, clean up and propagate the error.

If we really do deliberately ignore the error then there should be a
code comment which excuses this behaviour and perhaps a warning printk.

The same comments apply to mmci_set_ios().

omap_hsmmc_1_set_power() gets it right.

Why doesn't omap_hsmmc_23_set_sleep() run .before_set_reg() and
.after_set_reg()?

>
> ...
>
--
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