[PATCH] MMC:dw_mmc:when disable biu_clk should check whether this clk is normal

["ping.gao" <ping.gao@samsung.com>]

some vendor not enable biu_clk , disable it will panic

exynos use ciu_clk ,not use biu_clk

Sorry, I can't follow the below changes.
Isn't we disable biu_clk in dw_mci_runtime_suspend(()?
How could that work because biu_clk is used for register
access, FIFO access, etc.

Signed-off-by: ping.gao <ping.gao@samsung.com>
---
 drivers/mmc/host/dw_mmc.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index c5db92bbb094..e737333a0727 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -3633,9 +3633,15 @@ int dw_mci_runtime_resume(struct device *dev)
 	if (host->slot &&
 	    (mmc_host_can_gpio_cd(host->slot->mmc) ||
 	     !mmc_card_is_removable(host->slot->mmc))) {
-		ret = clk_prepare_enable(host->biu_clk);
-		if (ret)
-			return ret;
+		if (IS_ERR(host->biu_clk)) {
+			dev_dbg(host->dev, "biu clock not available\n");
+		} else {
+			ret = clk_prepare_enable(host->biu_clk);
+			if (ret) {
+				dev_err(host->dev, "failed to enable biu clock\n");
+				goto err;
+			}
+		}
 	}
 
 	ret = clk_prepare_enable(host->ciu_clk);
@@ -3686,9 +3692,12 @@ int dw_mci_runtime_resume(struct device *dev)
 err:
 	if (host->slot &&
 	    (mmc_host_can_gpio_cd(host->slot->mmc) ||
-	     !mmc_card_is_removable(host->slot->mmc)))
-		clk_disable_unprepare(host->biu_clk);
-
+	     !mmc_card_is_removable(host->slot->mmc))) {
+		if (IS_ERR(host->biu_clk))
+			dev_dbg(host->dev, "biu clock not available\n");
+		else
+			clk_disable_unprepare(host->biu_clk);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(dw_mci_runtime_resume);
-- 
2.50.1