mmc: MMC-4.5 Data Tag Support

MMC-4.5 data tag feature will be used to store the file system meta-data
in the tagged region of eMMC. This will improve the write and subsequent
read transfer time for the meta data.

Signed-off-by: Saugata Das <saugata.das@linaro.org>
Tested-by: Venkatraman S <svenkatr@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 16 insertions, 5 deletions

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index e5a3c7b6dedb..f2020d37c658 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -1080,6 +1080,7 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
         struct mmc_blk_request *brq = &mqrq->brq;
         struct request *req = mqrq->req;
         struct mmc_blk_data *md = mq->data;
+        bool do_data_tag;
 
         /*
          * Reliable writes are used to implement Forced Unit Access and
@@ -1156,6 +1157,16 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
                 mmc_apply_rel_rw(brq, card, req);
 
         /*
+         * Data tag is used only during writing meta data to speed
+         * up write and any subsequent read of this meta data
+         */
+        do_data_tag = (card->ext_csd.data_tag_unit_size) &&
+                (req->cmd_flags & REQ_META) &&
+                (rq_data_dir(req) == WRITE) &&
+                ((brq->data.blocks * brq->data.blksz) >=
+                 card->ext_csd.data_tag_unit_size);
+
+        /*
          * Pre-defined multi-block transfers are preferable to
          * open ended-ones (and necessary for reliable writes).
          * However, it is not sufficient to just send CMD23,
@@ -1173,13 +1184,13 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
          * We'll avoid using CMD23-bounded multiblock writes for
          * these, while retaining features like reliable writes.
          */
-
-        if ((md->flags & MMC_BLK_CMD23) &&
-            mmc_op_multi(brq->cmd.opcode) &&
-            (do_rel_wr || !(card->quirks & MMC_QUIRK_BLK_NO_CMD23))) {
+        if ((md->flags & MMC_BLK_CMD23) && mmc_op_multi(brq->cmd.opcode) &&
+            (do_rel_wr || !(card->quirks & MMC_QUIRK_BLK_NO_CMD23) ||
+             do_data_tag)) {
                 brq->sbc.opcode = MMC_SET_BLOCK_COUNT;
                 brq->sbc.arg = brq->data.blocks |
-                        (do_rel_wr ? (1 << 31) : 0);
+                        (do_rel_wr ? (1 << 31) : 0) |
+                        (do_data_tag ? (1 << 29) : 0);
                 brq->sbc.flags = MMC_RSP_R1 | MMC_CMD_AC;
                 brq->mrq.sbc = &brq->sbc;
         }