From: Chris Boot <bootc@xxxxxxxxx> I was trying to get a Micro-SD card working over SPI today when I ran into an issue which made the card unusable. The card was probed correctly, and the msdos partition table was read, but then some command was sent that made the card go into a bad state and stay that way. Only a re-probe would get the card unstuck and only until just after the partition tables were read. After some digging I ran into a post [1] on the spi-devel-general mailing list where someone had exactly the same issue as me, but back in 2007. There was a patch attached which, after some cleanup, fixes the issue completely for me. I have tried this with 3 different Micro-SD cards, all of which suffered from the problem before the patch and none of which fail after the patch. The error shows up as lots of: mmcblk0: error -38 sending status comand, retrying mmcblk0: error -38 sending status comand, retrying mmcblk0: error -38 sending status comand, aborting 1 : http://permalink.gmane.org/gmane.linux.kernel.spi.devel/516 Signed-off-by: Chris Boot <bootc@xxxxxxxxx> Signed-off-by: Clément Péron <peron.clem@xxxxxxxxx> --- drivers/mmc/core/block.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c index a0b9102c4c6e..7bf94ed96506 100644 --- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -1370,6 +1370,16 @@ static void mmc_blk_data_prep(struct mmc_queue *mq, struct mmc_queue_req *mqrq, brq->data.blocks = card->host->max_blk_count; if (brq->data.blocks > 1) { + /* + * Some SD cards in SPI mode return a CRC error or even lock up + * completely when trying to read the last block using a + * multiblock read command. + */ + if (mmc_host_is_spi(card->host) && (rq_data_dir(req) == READ) && + (blk_rq_pos(req) + blk_rq_sectors(req) == + get_capacity(md->disk))) + brq->data.blocks--; + /* * After a read error, we redo the request one sector * at a time in order to accurately determine which -- 2.17.1
