mmc: Add .multi_io_quirk callback for multi I/O HW bug

Historically, we have been using MMC_CAP* to handle host HW issues and
currently the block layer uses MMC_CAP2_NO_MULTI_READ flag for a multi
I/O HW bug workaround.

There are a few tweaks needed to make MMC_CAP2_NO_MULTI_READ suite all
situations. Therefore let's add an optional host ops callback to enable
host drivers to return the number of blocks it allows per request.

In a future patch and when host drivers have converted to the new
callback, MMC_CAP2_NO_MULTI_READ shall be removed.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index ede41f05c392..adab9038f6f7 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -1402,6 +1402,16 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
                 if (card->host->caps2 & MMC_CAP2_NO_MULTI_READ &&
                     rq_data_dir(req) == READ)
                         brq->data.blocks = 1;
+
+                /*
+                 * Some controllers have HW issues while operating
+                 * in multiple I/O mode
+                 */
+                if (card->host->ops->multi_io_quirk)
+                        brq->data.blocks = card->host->ops->multi_io_quirk(card,
+                                                (rq_data_dir(req) == READ) ?
+                                                MMC_DATA_READ : MMC_DATA_WRITE,
+                                                brq->data.blocks);
         }
 
         if (brq->data.blocks > 1 || do_rel_wr) {