mmc: dw_mmc: fix num_slots setting

This patch make num_slots to 1 if pdata->num_slot is not
defined. Meanwhile, we need to make sure num_slots should
not larger that the supported slots
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/dw_mmc.c

@@ -2879,12 +2879,7 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
 		return ERR_PTR(-ENOMEM);
 
 	/* find out number of slots supported */
-	if (of_property_read_u32(dev->of_node, "num-slots",
-				&pdata->num_slots)) {
-		dev_info(dev,
-			 "num-slots property not found, assuming 1 slot is available\n");
-		pdata->num_slots = 1;
-	}
+	of_property_read_u32(np, "num-slots", &pdata->num_slots);
 
 	if (of_property_read_u32(np, "fifo-depth", &pdata->fifo_depth))
 		dev_info(dev,
@@ -2960,12 +2955,6 @@ int dw_mci_probe(struct dw_mci *host)
 		}
 	}
 
-	if (host->pdata->num_slots < 1) {
-		dev_err(host->dev,
-			"Platform data must supply num_slots.\n");
-		return -ENODEV;
-	}
-
 	host->biu_clk = devm_clk_get(host->dev, "biu");
 	if (IS_ERR(host->biu_clk)) {
 		dev_dbg(host->dev, "biu clock not available\n");
@@ -3124,7 +3113,15 @@ int dw_mci_probe(struct dw_mci *host)
 	if (host->pdata->num_slots)
 		host->num_slots = host->pdata->num_slots;
 	else
-		host->num_slots = SDMMC_GET_SLOT_NUM(mci_readl(host, HCON));
+		host->num_slots = 1;
+
+	if (host->num_slots < 1 ||
+	    host->num_slots > SDMMC_GET_SLOT_NUM(mci_readl(host, HCON))) {
+		dev_err(host->dev,
+			"Platform data must supply correct num_slots.\n");
+		ret = -ENODEV;
+		goto err_clk_ciu;
+	}
 
 	/*
 	 * Enable interrupts for command done, data over, data empty,