From: Chris Ball <cjb@laptop.org>
To: David Vrabel <david.vrabel@csr.com>
Cc: Nicolas Pitre <nico@fluxnic.net>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mmc@vger.kernel.org
Subject: Re: [PATCH 5/5] SDIO: put active devices into 1-bit mode during suspend
Date: Wed, 10 Feb 2010 10:17:51 -0500 [thread overview]
Message-ID: <m38wb115nk.fsf@pullcord.laptop.org> (raw)
In-Reply-To: <4B7298EF.4070604@csr.com> (David Vrabel's message of "Wed, 10 Feb 2010 11:30:55 +0000")
Hi David,
> Why? Is this for a specific card that doesn't support
> asynchronous card interrupts while in 4-bit mode? If so, I'd
> suggest a card quirk for this and only switch modes for these
> cards.
(As a check that we're on the same page -- sdio_disable_wide() is only
called if MMC_PM_KEEP_POWER is true, which means the system is going
to be suspended but the card will remain externally powered without
its clock.)
Under the circumstances above, it's a requirement of the SDIO spec
that moving to 1-bit mode must happen before stopping the clock if
the interrupt mechanism is to be used to wake the host, and the
chipset we've been using (Via VX855) fails to generate a wakeup if
the switch isn't made. Do you have experience of another chipset
that doesn't need the switch to 1-bit mode for a clockless wakeup?
Thanks,
- Chris.
--
Chris Ball <cjb@laptop.org>
One Laptop Per Child
next prev parent reply other threads:[~2010-02-10 15:26 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-09 20:29 [PATCH 0/5] SDIO support for "powered" suspend Nicolas Pitre
2010-02-09 20:29 ` [PATCH 1/5] SDIO: introduce API for special power management features Nicolas Pitre
2010-02-11 20:32 ` Andrew Morton
2010-02-11 20:57 ` Nicolas Pitre
2010-02-09 20:29 ` [PATCH 2/5] SDIO: sdhci support for suspend mode PM features Nicolas Pitre
2010-02-09 20:29 ` [PATCH 3/5] SDIO: Don't use CMD[357] as part of a powered SDIO resume Nicolas Pitre
2010-02-09 20:29 ` [PATCH 4/5] SDIO: kick the interrupt thread upon a resume Nicolas Pitre
2010-02-09 20:29 ` [PATCH 5/5] SDIO: put active devices into 1-bit mode during suspend Nicolas Pitre
2010-02-10 11:30 ` David Vrabel
2010-02-10 15:17 ` Chris Ball [this message]
2010-02-10 16:03 ` David Vrabel
2010-02-10 16:32 ` Chris Ball
2010-02-10 16:49 ` David Vrabel
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