MMC: DWMMC: Correct the CLKDIV register value
This patch corrects the divider value written to CLKDIV register.
Since SDCLKIN is divided inside controller by the DIVRATIO value set
in the CLKSEL register, we need to use the same output clock value to
calculate the CLKDIV value.
as per user manual: cclk_in = SDCLKIN / (DIVRATIO + 1)
Input parameter to mmc_clk is changed to dwmci_host, since
we need the same to read DWMCI_CLKSEL register.
This improves the read timing values for channel 0 on SMDK5250
from 0.288sec to 0.144sec
Signed-off-by: Rajeshwari S Shinde <rajeshwari.s@samsung.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
diff --git a/drivers/mmc/dw_mmc.c b/drivers/mmc/dw_mmc.c
index 4cec5aa..d45c15c 100644
--- a/drivers/mmc/dw_mmc.c
+++ b/drivers/mmc/dw_mmc.c
@@ -237,7 +237,7 @@
* host->bus_hz should be set from user.
*/
if (host->get_mmc_clk)
- sclk = host->get_mmc_clk(host->dev_index);
+ sclk = host->get_mmc_clk(host);
else if (host->bus_hz)
sclk = host->bus_hz;
else {
diff --git a/drivers/mmc/exynos_dw_mmc.c b/drivers/mmc/exynos_dw_mmc.c
index b3e5c5e..de8cdcc 100644
--- a/drivers/mmc/exynos_dw_mmc.c
+++ b/drivers/mmc/exynos_dw_mmc.c
@@ -29,9 +29,22 @@
dwmci_writel(host, DWMCI_CLKSEL, host->clksel_val);
}
-unsigned int exynos_dwmci_get_clk(int dev_index)
+unsigned int exynos_dwmci_get_clk(struct dwmci_host *host)
{
- return get_mmc_clk(dev_index);
+ unsigned long sclk;
+ int8_t clk_div;
+
+ /*
+ * Since SDCLKIN is divided inside controller by the DIVRATIO
+ * value set in the CLKSEL register, we need to use the same output
+ * clock value to calculate the CLKDIV value.
+ * as per user manual:cclk_in = SDCLKIN / (DIVRATIO + 1)
+ */
+ clk_div = ((dwmci_readl(host, DWMCI_CLKSEL) >> DWMCI_DIVRATIO_BIT)
+ & DWMCI_DIVRATIO_MASK) + 1;
+ sclk = get_mmc_clk(host->dev_index);
+
+ return sclk / clk_div;
}
static void exynos_dwmci_board_init(struct dwmci_host *host)