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[05/12] mmc: sdhci: reset sdclk before setting high speed enable

Message ID 1297762510-2696-6-git-send-email-arindam.nath@amd.com (mailing list archive)
State New, archived
Headers show

Commit Message

Arindam Nath Feb. 15, 2011, 9:35 a.m. UTC
None
diff mbox

Patch

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index b768839..5db0109 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1280,13 +1280,12 @@  static void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	else
 		ctrl &= ~SDHCI_CTRL_HISPD;
 
-	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1);
-
 	if (host->version >= SDHCI_SPEC_300) {
 		u16 ctrl_2;
 
 		ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
 		if (!(ctrl_2 & SDHCI_CTRL_PRESET_VAL_ENABLE)) {
+			sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1);
 			/*
 			 * We only need to set Driver Strength if the
 			 * preset value enable is not set.
@@ -1297,8 +1296,28 @@  static void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 				ctrl_2 |= SDHCI_CTRL_DRV_TYPE_C;
 
 			sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2);
+		} else {
+			/*
+			 * According to SDHC Spec v3.00, if the Preset Value
+			 * Enable in the Host Control 2 register is set, we
+			 * need to reset SD Clock Enable before changing High
+			 * Speed Enable to avoid generating clock gliches.
+			 */
+			u16 clk;
+
+			/* Reset SD Clock Enable */
+			clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+			clk &= ~SDHCI_CLOCK_CARD_EN;
+			sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+			sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1);
+
+			/* Re-enable SD Clock */
+			clk |= SDHCI_CLOCK_CARD_EN;
+			sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
 		}
-	}
+	} else
+		sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1);
 
 	/*
 	 * Some (ENE) controllers go apeshit on some ios operation,