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

Arindam Nath
2011-02-15T09:37:09Z

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.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
---
drivers/mmc/host/sdhci.c | 25 ++++++++++++++++++++++---
1 files changed, 22 insertions(+), 3 deletions(-)

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,
--
1.7.1