On 05/30/2014 02:40 PM, Kuninori Morimoto wrote:
From: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
In some controllers, when performing a multiple block read of
You've typoed in the subject: "lultiple".
one or two blocks, depending on the timing with which the
response register is read, the response value may not
be read properly.
Use single block read for this HW bug
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
---
drivers/mmc/card/block.c | 19 +++++++++++++++++--
include/linux/mmc/host.h | 3 +++
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 452782b..f3cbe37 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -1400,8 +1400,23 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
/* Some controllers can't do multiblock reads due to hw bugs */
if (card->host->caps2 & MMC_CAP2_NO_MULTI_READ &&
- rq_data_dir(req) == READ)
- brq->data.blocks = 1;
+ rq_data_dir(req) == READ) {
+
+ if (card->host->caps2 & MMC_CAP2_2BLKS_LIMIT) {
+ /*
+ * In some controllers, when performing a
+ * multiple block read of one or two blocks,
+ * depending on the timing with which the
+ * response register is read, the response
+ * value may not be read properly.
+ * Use single block read for this HW bug
+ */
+ if (brq->data.blocks == 2)
+ brq->data.blocks = 1;
I don't understand: previous code set 'brq->data.blocks' to 1 in any case
without your extra flag. Why there's a need to set it specifically for 2
blocks (and not set for a larger # of blocks)? This looks like an optimization
of some sort, not a workaround?..
+ } else {
+ brq->data.blocks = 1;
+ }
+ }
}
if (brq->data.blocks > 1 || do_rel_wr) {
WBR, Sergei
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