diff mbox

[v4,04/15] mmc: sdhci: reset sdclk before setting high speed enable

Message ID 1304578151-1775-5-git-send-email-arindam.nath@amd.com (mailing list archive)
State New, archived
Headers show

Commit Message

Arindam Nath May 5, 2011, 6:49 a.m. UTC 
As per Host Controller spec v3.00, we reset SDCLK before setting
High Speed Enable, and then set it back to avoid generating clock
gliches. Before enabling SDCLK again, we make sure the clock is
stable, so we use sdhci_set_clock().

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Tested-by: Philip Rakity <prakity@marvell.com>
---
 drivers/mmc/host/sdhci.c |   27 ++++++++++++++++++++++++---
 1 files changed, 24 insertions(+), 3 deletions(-)

Comments

Chris Ball May 11, 2011, 3:36 a.m. UTC | #1 
Hi,

On Thu, May 05 2011, Arindam Nath wrote:
> As per Host Controller spec v3.00, we reset SDCLK before setting
> High Speed Enable, and then set it back to avoid generating clock
> gliches. Before enabling SDCLK again, we make sure the clock is
> stable, so we use sdhci_set_clock().
>
> Signed-off-by: Arindam Nath <arindam.nath@amd.com>
> Reviewed-by: Philip Rakity <prakity@marvell.com>
> Tested-by: Philip Rakity <prakity@marvell.com>

Thanks, pushed to mmc-next for .40.

- Chris.
diff mbox

Patch

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 9f38317..309240c 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1243,13 +1243,12 @@  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.
@@ -1261,8 +1260,30 @@  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;
+			unsigned int clock;
+
+			/* 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 */
+			clock = host->clock;
+			host->clock = 0;
+			sdhci_set_clock(host, clock);
 		}
-	}
+	} else
+		sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL1);
 
 	/*
 	 * Some (ENE) controllers go apeshit on some ios operation,