diff options
Diffstat (limited to 'drivers/mmc/host/mmc_spi.c')
| -rw-r--r-- | drivers/mmc/host/mmc_spi.c | 40 |
1 files changed, 33 insertions, 7 deletions
diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c index 87e211df68a..72f8bde4877 100644 --- a/drivers/mmc/host/mmc_spi.c +++ b/drivers/mmc/host/mmc_spi.c @@ -279,8 +279,11 @@ static int mmc_spi_response_get(struct mmc_spi_host *host, * so it can always DMA directly into the target buffer. * It'd probably be better to memcpy() the first chunk and * avoid extra i/o calls... + * + * Note we check for more than 8 bytes, because in practice, + * some SD cards are slow... */ - for (i = 2; i < 9; i++) { + for (i = 2; i < 16; i++) { value = mmc_spi_readbytes(host, 1); if (value < 0) goto done; @@ -609,6 +612,7 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t, 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( @@ -636,8 +640,27 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t, * 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. + * + * 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!!! */ - switch (SPI_MMC_RESPONSE_CODE(scratch->status[0])) { + 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; @@ -668,8 +691,9 @@ mmc_spi_writeblock(struct mmc_spi_host *host, struct spi_transfer *t, /* 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); @@ -1204,10 +1228,12 @@ static int mmc_spi_probe(struct spi_device *spi) /* MMC and SD specs only seem to care that sampling is on the * rising edge ... meaning SPI modes 0 or 3. So either SPI mode - * should be legit. We'll use mode 0 since it seems to be a - * bit less troublesome on some hardware ... unclear why. + * should be legit. We'll use mode 0 since the steady state is 0, + * which is appropriate for hotplugging, unless the platform data + * specify mode 3 (if hardware is not compatible to mode 0). */ - spi->mode = SPI_MODE_0; + if (spi->mode != SPI_MODE_3) + spi->mode = SPI_MODE_0; spi->bits_per_word = 8; status = spi_setup(spi); |