mmc: sdhci-omap: Fix DCRC error handling during tuning

Commit 7d33c3581536 ("mmc: sdhci-omap: Workaround for Errata i802")
disabled DCRC interrupts during tuning. This write to the interrupt
enable register gets overwritten in sdhci_prepare_data() and the
interrupt is not in fact disabled. Fix this by disabling the interrupt
in the host->ier variable.

Fixes: 7d33c3581536 ("mmc: sdhci-omap: Workaround for Errata i802")
Cc: <stable@vger.kernel.org>
Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-omap.c

@@ -288,9 +288,9 @@ static int sdhci_omap_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	struct device *dev = omap_host->dev;
 	struct mmc_ios *ios = &mmc->ios;
 	u32 start_window = 0, max_window = 0;
+	bool dcrc_was_enabled = false;
 	u8 cur_match, prev_match = 0;
 	u32 length = 0, max_len = 0;
-	u32 ier = host->ier;
 	u32 phase_delay = 0;
 	int ret = 0;
 	u32 reg;
@@ -317,9 +317,10 @@ static int sdhci_omap_execute_tuning(struct mmc_host *mmc, u32 opcode)
 	 * during the tuning procedure. So disable it during the
 	 * tuning procedure.
 	 */
-	ier &= ~SDHCI_INT_DATA_CRC;
-	sdhci_writel(host, ier, SDHCI_INT_ENABLE);
-	sdhci_writel(host, ier, SDHCI_SIGNAL_ENABLE);
+	if (host->ier & SDHCI_INT_DATA_CRC) {
+		host->ier &= ~SDHCI_INT_DATA_CRC;
+		dcrc_was_enabled = true;
+	}
 
 	while (phase_delay <= MAX_PHASE_DELAY) {
 		sdhci_omap_set_dll(omap_host, phase_delay);
@@ -366,6 +367,9 @@ tuning_error:
 
 ret:
 	sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
+	/* Reenable forbidden interrupt */
+	if (dcrc_was_enabled)
+		host->ier |= SDHCI_INT_DATA_CRC;
 	sdhci_writel(host, host->ier, SDHCI_INT_ENABLE);
 	sdhci_writel(host, host->ier, SDHCI_SIGNAL_ENABLE);
 	return ret;