Re: Command Time-Out values in MMC

Tony Lindgren
2006-01-28T20:36:24Z

* andrzej zaborowski <balrogg@gmail.com> [060128 11:55]:
> Hi,
> while browsing the MMC driver sources I noticed that the CTO (Command
> Time-Out) register is written a value 0xff in one place (exactly,
> here: http://www.kernel.org/git/?p=linux/kernel/git/tmlind/linux-omap-2.6.git;a=blob;h=35708dbf9d8e0f41687caeb70e7dde3f216a86a9;hb=9ca18d5394c5e6b2c74ddc52abaed81df530ff1d;f=drivers/mmc/omap.c#l847),
> while the OMAP5910 documentation (exactly, this document:
> http://focus.ti.com/dsp/docs/dspsupporttechdocsc.tsp?sectionId=3&tabId=409&familyId=325&abstractName=spru680)
> states something like:
> [...]
> 0x01: One clock cycle
> 0xFD: 253 clock cycles
> The 0xFF and 0xFE cannot be used.
> [...]
>
> Is this intentional? It seems to cause no problems, but setting 0xfd
> instead also didn't break anything for me. Is this limit also
> mentioned in documentation for other OMAP boards?
> (If this is intentional, please ignore me.)

As far as I remember we're not using the command timeout currently and it
was expiring with some cards and causing false errors.

Basically some blocks on some cards take a really long time to write to.
And if the command timeout expires before the card is done, we get a
false error.

Tony