[PATCH V2 03/15] mmc: core: Add support for re-tuning before each request

[Adrian Hunter <adrian.hunter@intel.com>]

At the start of each request, re-tune if needed and
then hold off re-tuning again until the request is done.

Note that though there is one function that starts
requests (mmc_start_request) there are two that wait for
the request to be done (mmc_wait_for_req_done and
mmc_wait_for_data_req_done).  Also note that
mmc_wait_for_data_req_done can return even when the
request is not done (which allows the block driver
to prepare a newly arrived request while still
waiting for the previous request).

This patch ensures re-tuning is held for the duration
of a request.  Subsequent patches will also hold
re-tuning at other times when it might cause a
conflict.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
 drivers/mmc/core/core.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index e9ab5ff..6dad56d 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -192,9 +192,21 @@ static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
 	unsigned int i, sz;
 	struct scatterlist *sg;
 #endif
+	int err;
+
+	mmc_retune_hold(host);
+
 	if (mmc_card_removed(host->card))
 		return -ENOMEDIUM;
 
+	err = mmc_retune_recheck(host);
+	if (err) {
+		/* Retry path expects the clock to be held */
+		if (mrq->cmd->retries)
+			mmc_host_clk_hold(host);
+		return err;
+	}
+
 	if (mrq->sbc) {
 		pr_debug("<%s: starting CMD%u arg %08x flags %08x>\n",
 			 mmc_hostname(host), mrq->sbc->opcode,
@@ -427,12 +439,11 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
 			}
 		} else if (context_info->is_new_req) {
 			context_info->is_new_req = false;
-			if (!next_req) {
-				err = MMC_BLK_NEW_REQUEST;
-				break; /* return err */
-			}
+			if (!next_req)
+				return MMC_BLK_NEW_REQUEST;
 		}
 	}
+	mmc_retune_release(host);
 	return err;
 }
 
@@ -473,6 +484,8 @@ static void mmc_wait_for_req_done(struct mmc_host *host,
 		cmd->error = 0;
 		host->ops->request(host, mrq);
 	}
+
+	mmc_retune_release(host);
 }
 
 /**
-- 
1.9.1