Re: [PATCH] mmc_spi: do propper retry managment in the block layer - rewritten

[Matt Fleming <matt@console-pimps.org>]

[CC'ing Nicolas as he's the at91 mci driver maintainer]

On Tue, May 19, 2009 at 09:16:40AM +0200, Wolfgang Mües wrote:
> Matt,
> 
> Am Montag, 18. Mai 2009 schrieb Matt Fleming:
> > Ah, now I understand. I've also been contacted privately by someone
> > who says that they've been experiencing similar issues and that your
> > patch has fixed them. Clearly there are people out there with flaky
> > hardware ;-)
> 
> Hmmm... Every hardware is flaky. Put a piece of hardware near your 
> refrigerator or DECT base, and you will have EMP or HF problems.
> Or use your finger and generate ESD pulses.
> 
> I am using a piezo where I have the GND pin connected to a wire to generate 
> ESD pulses which have the same results as a 4 KV ESD generator:
> 
> http://www.vega-direct.at/buffet/chafing_dish_mit_zubehoer/gasanzuender/index.hsp
> 
> A software which do not behave gracefully in the presence of errors is not 
> production quality for me.
> 

Oh, wow. I didn't pick up on the fact that you were artificially
generating errors on the bus. I thought you'd seen this sort of
problem in production. I don't understand what sort of fault-tolerance
you expect the MMC/SD subsystem to provide.

I've heard from one person that an earlier version of this patch fixed
issues with their at91 controller. If othe people are experiencing
similar issues and this patch fixes it for them, then it definitely
lends some weight to it.

Nicolas, do you have an opinion on the patch?