Messages in this thread Patch in this message | | | From | Wolfgang Mües <> | Subject | [PATCH 4/7 revised] mmc_spi: do not check CID and CSD blocks with CRC16 | Date | Wed, 18 Mar 2009 10:52:39 +0100 |
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From: Wolfgang Muees <wolfgang.mues@auerswald.de>
o Some cards are not able to calculate a valid CRC16 value for CID and CSD reads (CRC for 512 byte data blocks is OK). So ommit the check for CRC16, as CID and CSD have a checksum inside the block.
Signed-off-by: Wolfgang Muees <wolfgang.mues@auerswald.de>
---
This is patch #4 revised to apply after #1,#2,#5 (already applied) and #3 (acked by David Brownell). Documentation was extended. There were some suggestions to move this check into an upper layer but none of these tries were a valid solution, so stick with this minimal change here in the readblock function.
diff -uprN 2_6_29_rc7_patch1253/drivers/mmc/host/mmc_spi.c 2_6_29_rc7_patch12534/drivers/mmc/host/mmc_spi.c --- 2_6_29_rc7_patch1253/drivers/mmc/host/mmc_spi.c 2009-03-16 12:15:36.000000000 +0100 +++ 2_6_29_rc7_patch12534/drivers/mmc/host/mmc_spi.c 2009-03-18 10:32:45.000000000 +0100 @@ -767,7 +767,13 @@ mmc_spi_readblock(struct mmc_spi_host *h return -EIO; } - if (host->mmc->use_spi_crc) { + /* Omitt the CRC check for CID reads. There are some SDHC + * cards which don't supply a valid CRC after CID reads. + * All data reads have len == MMC_SPI_BLOCKSIZE, so use this + * check to distinguish between data reads and CID/CSD reads. + * Note that CID/CSD has it's own CRC7 value inside the structure. + */ + if (host->mmc->use_spi_crc && (t->len == MMC_SPI_BLOCKSIZE)) { u16 crc = crc_itu_t(0, t->rx_buf, t->len); be16_to_cpus(&scratch->crc_val); --- 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 -- 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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