Messages in this thread | | | From | David Brownell <> | Subject | Re: [PATCH 3/7 revised] mmc_spi: adjust for delayed data token response | Date | Mon, 16 Mar 2009 12:37:36 -0700 |
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On Monday 16 March 2009, Wolfgang Mües wrote: > From: Wolfgang Muees <wolfgang.mues@auerswald.de> > > o some cards are not able to send the data token in time, but > miss the time frame for some bits(!). So synchronize to the > start of the token. > > Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
> --- > > This is the revised patch #3, to apply after the already accepted > patches #1,2 and #5. It contains the bugfix and a better explanation > of what is going on here. > > diff -uprN 2_6_29_rc7_patch125/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch1253/drivers/mmc/host/mmc_spi.c > --- 2_6_29_rc7_patch125/drivers/mmc/host/mmc_spi.c 2009-03-11 13:00:06.000000000 +0100 > +++ 2_6_29_rc7_patch1253/drivers/mmc/host/mmc_spi.c 2009-03-16 12:15:36.000000000 +0100 > @@ -612,6 +612,7 @@ mmc_spi_writeblock(struct mmc_spi_host * > struct spi_device *spi = host->spi; > int status, i; > struct scratch *scratch = host->data; > + u32 pattern; > > if (host->mmc->use_spi_crc) > scratch->crc_val = cpu_to_be16( > @@ -639,8 +640,27 @@ mmc_spi_writeblock(struct mmc_spi_host * > * doesn't necessarily tell whether the write operation succeeded; > * it just says if the transmission was ok and whether *earlier* > * writes succeeded; see the standard. > - */ > - switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) { > + * > + * In practice, there are (even modern SDHC-)cards which are late > + * in sending the response, and miss the time frame by a few bits, > + * so we have to cope with this situation and check the response > + * bit-by-bit. Arggh!!! > + */ > + pattern = scratch->status[0] << 24; > + pattern |= scratch->status[1] << 16; > + pattern |= scratch->status[2] << 8; > + pattern |= scratch->status[3]; > + > + /* First 3 bit of pattern are undefined */ > + pattern |= 0xE0000000; > + > + /* left-adjust to leading 0 bit */ > + while (pattern & 0x80000000) > + pattern <<= 1; > + /* right-adjust for pattern matching. Code is in bit 4..0 now. */ > + pattern >>= 27; > + > + switch (pattern) { > case SPI_RESPONSE_ACCEPTED: > status = 0; > break; > @@ -671,8 +691,9 @@ mmc_spi_writeblock(struct mmc_spi_host * > /* Return when not busy. If we didn't collect that status yet, > * we'll need some more I/O. > */ > - for (i = 1; i < sizeof(scratch->status); i++) { > - if (scratch->status[i] != 0) > + for (i = 4; i < sizeof(scratch->status); i++) { > + /* card is non-busy if the most recent bit is 1 */ > + if (scratch->status[i] & 0x01) > return 0; > } > return mmc_spi_wait_unbusy(host, timeout); > > --- > regards > > i. A. Wolfgang Mües > -- > Auerswald GmbH & Co. KG > Hardware Development > Telefon: +49 (0)5306 9219 0 > Telefax: +49 (0)5306 9219 94 > E-Mail: Wolfgang.Mues@Auerswald.de > Web: http://www.auerswald.de > > -------------------------------------------------------------- > Auerswald GmbH & Co. KG, Vor den Grashöfen 1, 38162 Cremlingen > Registriert beim AG Braunschweig HRA 13289 > p.h.G Auerswald Geschäftsführungsges. mbH > Registriert beim AG Braunschweig HRB 7463 > Geschäftsführer: Dipl-Ing. Gerhard Auerswald > >
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