linux-kernel - Re: [PATCH] mmc_core: fix data timeout for SEND_EXT

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Message-ID: <499D4CB6.3070807@nokia.com>
Date:	Thu, 19 Feb 2009 14:12:38 +0200
From:	Adrian Hunter <ext-adrian.hunter@...ia.com>
To:	Matt Fleming <matt@...sole-pimps.org>
CC:	Pierre Ossman <drzeus-mmc@...eus.cx>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc_core: fix data timeout for SEND_EXT_CSD

Matt Fleming wrote:
> On Thu, Feb 19, 2009 at 09:33:48AM +0200, Adrian Hunter wrote:
>> ext Pierre Ossman wrote:
>>> I'm confused. Where did the 64 come from in the first place? That
>>> function will not be called for CID/CSD when !SPI. So the way I see it
>>> the code should be:
>>>
>>> if ((opcode == MMC_SEND_CSD) || (opcode == (MMC_SEND_CID)) {
>>>         data.timeout_ns = 0;
>>>         data.timeout_clks = 8;
>>> } else {
>>>         mmc_set_data_timeout(&data, card);
>>> }
>> Theoretically yes, it should be 8 not 64 - if all the SPI devices obey
>> the standard.  As I do not have an SPI device I did not feel comfortable
>> changing it.  Also 64 clocks is not a long time anyway, so it did not
>> seem to do any harm.
> 
> When I wrote the code, I got the 64 clock cycle timeout from the MMC
> spec that I was looking at. Unfortunately, I don't have the spec in
> front of me at the moment. It is possible that I read the timeout for
> the !SPI case, though.

No it is my mistake.  The value is 8 but the unit is 8 clock cycles
i.e. 64 clock cycles.  So my comment was wrong.

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