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From: David Vrabel <david.vrabel@csr.com>
To: Linus Walleij <linus.walleij@stericsson.com>
Cc: linux-mmc@vger.kernel.org, Ghorai Sukumar <s-ghorai@ti.com>,
	Chris Ball <cjb@laptop.org>, Nicolas Pitre <nico@fluxnic.net>,
	Adrian Hunter <adrian.hunter@nokia.com>
Subject: Re: [PATCH] MMC Agressive clocking framework v6
Date: Mon, 01 Nov 2010 11:27:49 +0000	[thread overview]
Message-ID: <4CCEA435.9030402@csr.com> (raw)
In-Reply-To: <1288383487-29860-1-git-send-email-linus.walleij@stericsson.com>

On 29/10/2010 21:18, Linus Walleij wrote:
> This patch modifies the MMC core code to optionally call the
> set_ios() operation on the driver with the clock frequency set
> to 0 (gate) after a grace period of at least 8 MCLK cycles, then
> restore it (ungate) before any new request. This gives
> the driver the option to shut down the MCI clock to the MMC/SD
> card when the clock frequency is 0, i.e. the core has stated
> that the MCI clock does not need to be generated.

With SDIO cards, 1 bit mode needs to be set on the controller otherwise
many controllers cannot detect card interrupts.

Also some v2.00 SDIO cards in 4-bit mode will not generate card
interrupts unless they are clocked (the spec v2.00 doesn't require them
to be able to but v3.00 does).  I would suggest a white list of v2.00
cards that can generate interrupts asynchronousy.

David

  parent reply	other threads:[~2010-11-01 11:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-29 20:18 [PATCH] MMC Agressive clocking framework v6 Linus Walleij
2010-10-30  5:04 ` Kyungmin Park
2010-11-01 11:27 ` David Vrabel [this message]
2010-11-01 15:24   ` Linus Walleij
2010-11-01 15:27     ` David Vrabel

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