[PATCH 4.18 128/135] mmc: block: avoid multiblock reads for the last sector in SPI mode

Greg Kroah-Hartman
2018-10-16T17:17:01Z

From: Chris Boot <bootc@bootc.net>

commit 41591b38f5f8f78344954b68582b5f00e56ffe61 upstream.

On some SD cards over SPI, reading with the multiblock read command the last
sector will leave the card in a bad state.

Remove last sectors from the multiblock reading cmd.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Clément Péron <peron.clem@gmail.com>
Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/core/block.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1371,6 +1371,16 @@ static void mmc_blk_data_prep(struct mmc

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
* sectors can be read successfully.