Messages in this thread | | | Date | Wed, 11 Mar 2009 14:38:09 +0000 | Subject | Re: [PATCH 7/7] mmc_spi: support for non-byte-aligned cards | From | Will Newton <> |
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On Wed, Mar 11, 2009 at 2:34 PM, Wolfgang Mües <wolfgang.mues@auerswald.de> wrote: > Will, > > Am Mittwoch, 11. März 2009 schrieb Will Newton: >> <wolfgang.mues@auerswald.de> wrote: >> > From: Wolfgang Muees <wolfgang.mues@auerswald.de> >> > >> > o A very large subset of SD cards in the market send their >> > responses and data non-byte-aligned. So add logic to the >> > mmc spi driver to handle this mess. >> >> Are you sure about this? > > Yes. > >> Do you have any further references for this >> or examples of cards that exhibit this problem? > > Kingston. The 1 GByte SD card, and a 128 MByte microSD card. I have got some > reports from other mmc spi users with the same problem.
Are they using the same host controller? Have you tried these cards with a different host controller?
Are you clocking them particularly slow or fast?
> The SD protocoll ist NOT byte-aligned. Messages are starting with a > leading "0" bit. I think some chip vendors have adapted the SPI mode from SD > mode and forgotten to do propper byte alignment. > >> Are you sure your SPI host controller is operating correctly? > > Yes. My logic probe gives the same results as my spi host controller. > For some cards, you can see the bit offset is getting larger if the > controller on the SD card is getting more and more busy...
A logic probe may not display any signal integrity issues you might have. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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