Re: mmc_test Correct xfer_size at write

[James Hogan <james.hogan@imgtec.com>]

On 06/28/2011 05:50 PM, Pierre Ossman wrote:
> On Tue, 28 Jun 2011 11:37:25 +0100
> James Hogan <james.hogan@imgtec.com> wrote:
> 
>> Hi,
>>
>> I'm trying to figure out why the broken write transfer tests in mmc_test
>> require the result to be -ETIMEDOUT, so that I can make dw_mmc pass
>> these tests. Perhaps somebody could explain.
>>
>> I can understand for reads, that the controller is waiting for the start
>> bit on the data lines and so it can timeout after a while if it doesn't
>> see any. However for writes (as far as I can glean from the physical
>> layer spec and a logic analyser) the data response token which is
>> normally sent by the card in response to a write transfer is clocked out
>> immediately after the data so is either there or it isn't.
>>
>> Have I misunderstood it or is -ETIMEDOUT just the error that is required
>> by convention when the data response token is not detected?
>>
> 
> It's more or less by convention. ETIMEDOUT is the closest thing we have
> to "we expected a response from the card but got bupkis". You can find
> some informal definitions here:
> 
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=include/linux/mmc/core.h;h=b6718e549a510780e0f8c9a3be17e64753d6c2f5;hb=HEAD#l81
> 
> Rgds

Thanks for the info Pierre

James