mmc: sdhci: Fix CMD line reset interfering with ongoing data transfer

CMD line reset during an ongoing data transfer can cause the data transfer
to hang.  Fix by delaying the reset until the data transfer is finished.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org # v4.8+
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -2286,10 +2286,8 @@ static bool sdhci_request_done(struct sdhci_host *host)
 
 	for (i = 0; i < SDHCI_MAX_MRQS; i++) {
 		mrq = host->mrqs_done[i];
-		if (mrq) {
-			host->mrqs_done[i] = NULL;
+		if (mrq)
 			break;
-		}
 	}
 
 	if (!mrq) {
@@ -2320,6 +2318,17 @@ static bool sdhci_request_done(struct sdhci_host *host)
 	 * upon error conditions.
 	 */
 	if (sdhci_needs_reset(host, mrq)) {
+		/*
+		 * Do not finish until command and data lines are available for
+		 * reset. Note there can only be one other mrq, so it cannot
+		 * also be in mrqs_done, otherwise host->cmd and host->data_cmd
+		 * would both be null.
+		 */
+		if (host->cmd || host->data_cmd) {
+			spin_unlock_irqrestore(&host->lock, flags);
+			return true;
+		}
+
 		/* Some controllers need this kick or reset won't work here */
 		if (host->quirks & SDHCI_QUIRK_CLOCK_BEFORE_RESET)
 			/* This is to force an update */
@@ -2327,10 +2336,8 @@ static bool sdhci_request_done(struct sdhci_host *host)
 
 		/* Spec says we should do both at the same time, but Ricoh
 		   controllers do not like that. */
-		if (!host->cmd)
-			sdhci_do_reset(host, SDHCI_RESET_CMD);
-		if (!host->data_cmd)
-			sdhci_do_reset(host, SDHCI_RESET_DATA);
+		sdhci_do_reset(host, SDHCI_RESET_CMD);
+		sdhci_do_reset(host, SDHCI_RESET_DATA);
 
 		host->pending_reset = false;
 	}
@@ -2338,6 +2345,8 @@ static bool sdhci_request_done(struct sdhci_host *host)
 	if (!sdhci_has_requests(host))
 		sdhci_led_deactivate(host);
 
+	host->mrqs_done[i] = NULL;
+
 	mmiowb();
 	spin_unlock_irqrestore(&host->lock, flags);