Messages in this thread | | | Date | Thu, 8 Jan 2009 09:24:07 +0000 | From | Matt Fleming <> | Subject | Re: [PATCH] Fixes and enhancements for the MMC SPI driver |
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On Thu, Jan 08, 2009 at 09:22:08AM +0100, Wolfgang M?es wrote: > Matt, > > Am Dienstag, 6. Januar 2009 schrieb Matt Fleming: > > Which cards are you having issues with? > > This was a noname 4 GByte SDHC card. If you write a continious stream of data > at max. speed, the card generates a BUSY signal every 10 seconds for nearly a > whole second. >
Ouch :-/
> > Modifying the code to no longer abide by the standard doesn't seem like a > > win to me. > > I strongly disagree with you. > > While each and every SD card should conform to the standard, a driver for a > host controller should be as forgiving as possible. If the driver cannot cope > with cards sold today, the user has a bad experience. > > I code drivers for people and not for standards. > > Remember, this is only a timeout. Lengthen the timeout will have no > consequences for cards which behave.
My concern is that completely broken cards may be able to get away with more if the timeout is extended. There is clearly a tradeoff here between supporting non-conforming cards and easily detecting broken cards.
Someone suggested to me off list that having a configuration option to enable/disable the longer timeout is a good compromise, and I agree.
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