linux-kernel - Re: [PATCH 3/3] mmc: change .get

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Date:	Tue, 3 Jun 2008 12:07:49 +0200
From:	Marc Pignat <marc.pignat@...s.ch>
To:	Anton Vorontsov <avorontsov@...mvista.com>
Cc:	Kumar Gala <galak@...nel.crashing.org>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	Pierre Ossman <drzeus-mmc@...eus.cx>,
	Jochen Friedrich <jochen@...am.de>,
	Timur Tabi <timur@...escale.com>, linuxppc-dev@...abs.org,
	linux-kernel@...r.kernel.org,
	spi-devel-general@...ts.sourceforge.net
Subject: Re: [PATCH 3/3] mmc: change .get_ro() callback semantics

Hi all!

On Friday 23 May 2008, Anton Vorontsov wrote:
> get_ro() callback must return values >= 0 for its logical state, and
...
>  static void pxamci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index f2e9885..ef3b773 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -55,6 +55,9 @@ struct mmc_host_ops {
>  	 * Avoid calling these three functions too often or in a "fast path",
>  	 * since underlaying controller might implement them in an expensive
>  	 * and/or slow way.
> +	 *
> +	 * .get_ro and .get_cd should return >= 0 for their logical values,
> +	 * or negative errno value in case of error.
>  	 */

I would suggest to use something more strict (bulletproof), something like:

/*
 * get_ro will return:
 *   0 for a read/write card
 *   1 for a read-only card 
 *   -ENOSYS when not supported
 *   or a negative errno when something bad happened
 * 
 * get_cd will return:
 *   0 for a absent card
 *   1 for a present card 
 *   -ENOSYS when not supported
 *   or a negative errno when something bad happened
 */

I think we have missed one important information: which context these callbacks
can rely on (hard_irq, soft_irq, ...).



Best regards

Marc

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