mmc: Retry a read/write req when error is EAGAIN

If the error returned for a read/write operation is EAGAIN,
execute the request again.

A host driver may utilize this option to trigger a retry of
the exact same request, which may be useful for HW workarounds.

ST-Ericsson Linux next:
ST-Ericsson ID: 342919
ST-Ericsson FOSS-OUT ID: Trivial

Change-Id: Ia14af2f2324fe8f2cbfe4b6cd07fb39b3209ec4f
Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
Reviewed-on: http://gerrit.lud.stericsson.com/gerrit/25169
Reviewed-by: Sebastian RASMUSSEN <sebastian.rasmussen@stericsson.com>
Reviewed-by: P.Hanumath PRASAD <hanumath.prasad@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>

1 files changed, 45 insertions, 34 deletions

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 61d233a7c11..10950dab1e9 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -245,7 +245,10 @@ static u32 mmc_sd_num_wr_blocks(struct mmc_card *card)
 	return result;
 }
 
-static u32 get_card_status(struct mmc_card *card, struct request *req)
+static int get_card_status(struct mmc_card *card,
+				struct request *req,
+				u32 *status,
+				int retries)
 {
 	struct mmc_command cmd;
 	int err;
@@ -255,11 +258,38 @@ static u32 get_card_status(struct mmc_card *card, struct request *req)
 	if (!mmc_host_is_spi(card->host))
 		cmd.arg = card->rca << 16;
 	cmd.flags = MMC_RSP_SPI_R2 | MMC_RSP_R1 | MMC_CMD_AC;
-	err = mmc_wait_for_cmd(card->host, &cmd, 0);
+	err = mmc_wait_for_cmd(card->host, &cmd, retries);
 	if (err)
 		printk(KERN_ERR "%s: error %d sending status command",
 		       req->rq_disk->disk_name, err);
-	return cmd.resp[0];
+	else
+		*status = cmd.resp[0];
+
+	return err;
+}
+
+static int wait_for_ready_state(struct mmc_card *card, struct request *req)
+{
+	u32 status;
+	int err = 0;
+
+	if (!mmc_host_is_spi(card->host) && rq_data_dir(req) != READ) {
+
+		do {
+			err = get_card_status(card, req, &status, 5);
+			if (err)
+				break;
+
+			/*
+			 * Some cards mishandle the status bits,
+			 * so make sure to check both the busy
+			 * indication and the card state.
+			 */
+		} while (!(status & R1_READY_FOR_DATA) ||
+			(R1_CURRENT_STATE(status) == 7));
+	}
+
+	return err;
 }
 
 static int mmc_blk_issue_discard_rq(struct mmc_queue *mq, struct request *req)
@@ -341,7 +371,6 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 	mmc_claim_host(card->host);
 
 	do {
-		struct mmc_command cmd;
 		u32 readcmd, writecmd, status = 0;
 
 		memset(&brq, 0, sizeof(struct mmc_blk_request));
@@ -431,6 +460,15 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 		 * until later as we need to wait for the card to leave
 		 * programming mode even when things go wrong.
 		 */
+		if (!brq.cmd.error && !brq.stop.error &&
+			brq.data.error == -EAGAIN) {
+			printk(KERN_WARNING "%s: retrying transfer\n",
+					req->rq_disk->disk_name);
+			if (wait_for_ready_state(card, req))
+				goto cmd_err;
+			continue;
+		}
+
 		if (brq.cmd.error || brq.data.error || brq.stop.error) {
 			if (brq.data.blocks > 1 && rq_data_dir(req) == READ) {
 				/* Redo read one sector at a time */
@@ -439,7 +477,7 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 				disable_multi = 1;
 				continue;
 			}
-			status = get_card_status(card, req);
+			get_card_status(card, req, &status, 0);
 		}
 
 		if (brq.cmd.error) {
@@ -467,35 +505,8 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *req)
 			       brq.stop.resp[0], status);
 		}
 
-		if (!mmc_host_is_spi(card->host) && rq_data_dir(req) != READ) {
-			do {
-				int err;
-
-				cmd.opcode = MMC_SEND_STATUS;
-				cmd.arg = card->rca << 16;
-				cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
-				err = mmc_wait_for_cmd(card->host, &cmd, 5);
-				if (err) {
-					printk(KERN_ERR "%s: error %d requesting status\n",
-					       req->rq_disk->disk_name, err);
-					goto cmd_err;
-				}
-				/*
-				 * Some cards mishandle the status bits,
-				 * so make sure to check both the busy
-				 * indication and the card state.
-				 */
-			} while (!(cmd.resp[0] & R1_READY_FOR_DATA) ||
-				(R1_CURRENT_STATE(cmd.resp[0]) == 7));
-
-#if 0
-			if (cmd.resp[0] & ~0x00000900)
-				printk(KERN_ERR "%s: status = %08x\n",
-				       req->rq_disk->disk_name, cmd.resp[0]);
-			if (mmc_decode_status(cmd.resp))
-				goto cmd_err;
-#endif
-		}
+		if (wait_for_ready_state(card, req))
+			goto cmd_err;
 
 		if (brq.cmd.error || brq.stop.error || brq.data.error) {
 			if (rq_data_dir(req) == READ) {