[PATCH 4.14 073/109] mmc: block: avoid multiblock reads for the last sector in SPI mode

[Greg Kroah-Hartman]

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chris Boot <bootc@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: ClÃment PÃron <peron.clem@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v4.10+
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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

--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -1614,6 +1614,16 @@ 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.