Date: Tue, 24 Oct 2006 13:14:58 +0300
From: Timo Teras <timo.teras@solidboot.com>
To: Pierre Ossman <drzeus-list@drzeus.cx>
Cc: Timo Teras <timo.teras@solidboot.com>, linux-kernel@vger.kernel.org
Subject: Re: MMC: When rescanning cards check existing cards after mmc_setup()
Message-ID: <20061024101458.GA17024@mail.solidboot.com>
References: <20061016090609.GB17596@mail.solidboot.com> <453B4005.8080501@drzeus.cx>
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On Sun, Oct 22, 2006 at 11:55:17AM +0200, Pierre Ossman wrote:
> Timo Teras wrote:
> > Some broken cards seem to process CMD1 even in stand-by state. The result is
> > that the card replies with ILLEGAL_COMMAND error for the next command sent
> > after rescanning. Currently the next command is select card, which would
> > return the error. But the CMD7 does actually succeed and retries of the
> > command will timeout. The solution is to poll card status after the CMD1
> > which clears the cached error.
>
> I take it these cards do not reply to CMD2?

No. It just caches the error and fails the next command sent.

> This change is ok right now, but might come back to bite us in the
> future if we implement more intelligent voltage selection (right now new
> cards will have to make due with what's already selected).

I see. The voltage selection is done in mmc_setup() based on what cards are
present.

> If we check cards on both sides of mmc_setup(), then we should be covered.

Should I update my patch to do this already? Or is the code fine as is?

> Also, please add some comments about why we do this. Otherwise it will
> run the risk of getting removed in the future.

Will do.

I'll send updated patch later on.

-- Timo

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