mmc: core: Add support for re-tuning before each request

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.

In addition, possibly a command is failing because
re-tuning is needed. Use mmc_retune_recheck() to check
re-tuning. At that point re-tuning is held, at least by
the request, so mmc_retune_recheck() flags host->retune_now
if the hold count is 1.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 007c44443332cf0551ab5fe66756b3e7a62931d8..ec3453fd39aa3c33fa22720d9b6c655172aad4d0 100644 (file)
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -186,12 +186,29 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
 
 EXPORT_SYMBOL(mmc_request_done);
 
+static void __mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
+{
+       int err;
+
+       /* Assumes host controller has been runtime resumed by mmc_claim_host */
+       err = mmc_retune(host);
+       if (err) {
+               mrq->cmd->error = err;
+               mmc_request_done(host, mrq);
+               return;
+       }
+
+       host->ops->request(host, mrq);
+}
+
 static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
 {
 #ifdef CONFIG_MMC_DEBUG
        unsigned int i, sz;
        struct scatterlist *sg;
 #endif
+       mmc_retune_hold(host);
+
        if (mmc_card_removed(host->card))
                return -ENOMEDIUM;
 
@@ -252,7 +269,7 @@ static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
        }
        mmc_host_clk_hold(host);
        led_trigger_event(host->led, LED_FULL);
-       host->ops->request(host, mrq);
+       __mmc_start_request(host, mrq);
 
        return 0;
 }
@@ -417,22 +434,22 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
                                                            host->areq);
                                break; /* return err */
                        } else {
+                               mmc_retune_recheck(host);
                                pr_info("%s: req failed (CMD%u): %d, retrying...\n",
                                        mmc_hostname(host),
                                        cmd->opcode, cmd->error);
                                cmd->retries--;
                                cmd->error = 0;
-                               host->ops->request(host, mrq);
+                               __mmc_start_request(host, mrq);
                                continue; /* wait for done/new event again */
                        }
                } 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;
 }
 
@@ -467,12 +484,16 @@ static void mmc_wait_for_req_done(struct mmc_host *host,
                    mmc_card_removed(host->card))
                        break;
 
+               mmc_retune_recheck(host);
+
                pr_debug("%s: req failed (CMD%u): %d, retrying...\n",
                         mmc_hostname(host), cmd->opcode, cmd->error);
                cmd->retries--;
                cmd->error = 0;
-               host->ops->request(host, mrq);
+               __mmc_start_request(host, mrq);
        }
+
+       mmc_retune_release(host);
 }
 
 /**