linux-kernel - [PATCH] sdhci: Be more strict with get_min

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Message-ID: <20090804172055.GA9271@oksana.dev.rtsoft.ru>
Date:	Tue, 4 Aug 2009 21:20:55 +0400
From:	Anton Vorontsov <avorontsov@...mvista.com>
To:	Pierre Ossman <pierre@...man.eu>
Cc:	akpm@...ux-foundation.org, drzeus@...eus.cx, ian@...menth.co.uk,
	matt@...sole-pimps.org, roberto.foglietta@...il.com,
	linux-kernel@...r.kernel.org, sdhci-devel@...ts.ossman.eu
Subject: [PATCH] sdhci: Be more strict with get_min_clock() usage

get_min_clock() makes sense only with NONSTANDARD_CLOCK quirk and when
set_clock() callback is specified.

The patch should cause no functional changes, it just makes the code
self-documented and avoids any possible misuse of get_min_clock().

Suggested-by: Pierre Ossman <pierre@...man.eu>
Signed-off-by: Anton Vorontsov <avorontsov@...mvista.com>
---

On Sat, Aug 01, 2009 at 10:04:43AM +0200, Pierre Ossman wrote:
[...]
> Hmm... I don't think this is quite right. Right now you kill the
> warning without verifying that there is a mechanism to go lower.
[...]
> > -	mmc->f_min = host->max_clk / 256;
> > +	if (host->ops->get_min_clock)
> > +		mmc->f_min = host->ops->get_min_clock(host);
> > +	else
> > +		mmc->f_min = host->max_clk / 256;
> >  	mmc->f_max = host->max_clk;
> >  	mmc->caps = MMC_CAP_SDIO_IRQ;
> 
> You should be checking ops->set_clock and SDHCI_QUIRK_NONSTANDARD_CLOCK
> here.

Well, it makes no sense to specify .get_min_clock() w/o .set_clock().

But okay, to make things self documented and to avoid misuses, we'd
better add these checks.

Thanks Pierre!

 drivers/mmc/host/sdhci.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index fc96f8c..7f7f45b 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1772,7 +1772,8 @@ int sdhci_add_host(struct sdhci_host *host)
 	 * Set host parameters.
 	 */
 	mmc->ops = &sdhci_ops;
-	if (host->ops->get_min_clock)
+	if (host->quirks & SDHCI_QUIRK_NONSTANDARD_CLOCK &&
+			host->ops->set_clock && host->ops->get_min_clock)
 		mmc->f_min = host->ops->get_min_clock(host);
 	else
 		mmc->f_min = host->max_clk / 256;
-- 
1.6.3.3

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