[MMC] Fix SD timeout calculation

Secure Digital cards use a different algorithm to calculate the timeout
for data transfers. Using the MMC one works often, but not always.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/mmc/mmc.c

@@ -912,6 +912,7 @@ static void mmc_read_scrs(struct mmc_host *host)
 	struct mmc_request mrq;
 	struct mmc_command cmd;
 	struct mmc_data data;
+	unsigned int timeout_us;
 
 	struct scatterlist sg;
 
@@ -947,8 +948,18 @@ static void mmc_read_scrs(struct mmc_host *host)
 
 		memset(&data, 0, sizeof(struct mmc_data));
 
-		data.timeout_ns = card->csd.tacc_ns * 10;
-		data.timeout_clks = card->csd.tacc_clks * 10;
+		data.timeout_ns = card->csd.tacc_ns * 100;
+		data.timeout_clks = card->csd.tacc_clks * 100;
+
+		timeout_us = data.timeout_ns / 1000;
+		timeout_us += data.timeout_clks * 1000 /
+			(host->ios.clock / 1000);
+
+		if (timeout_us > 100000) {
+			data.timeout_ns = 100000000;
+			data.timeout_clks = 0;
+		}
+
 		data.blksz_bits = 3;
 		data.blksz = 1 << 3;
 		data.blocks = 1;