mmc: atmel-mci: fix bad variable type for clkdiv

commit 60c8f783 upstream.

clkdiv is declared as an u32 but it can be set to a negative value
causing a huge divisor value. Change its type to int to avoid this case.
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/mmc/host/atmel-mci.c

@@ -1294,7 +1294,7 @@ static void atmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 
 	if (ios->clock) {
 		unsigned int clock_min = ~0U;
-		u32 clkdiv;
+		int clkdiv;
 
 		clk_prepare(host->mck);
 		unprepare_clk = true;
@@ -1323,7 +1323,12 @@ static void atmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 		/* Calculate clock divider */
 		if (host->caps.has_odd_clk_div) {
 			clkdiv = DIV_ROUND_UP(host->bus_hz, clock_min) - 2;
-			if (clkdiv > 511) {
+			if (clkdiv < 0) {
+				dev_warn(&mmc->class_dev,
+					 "clock %u too fast; using %lu\n",
+					 clock_min, host->bus_hz / 2);
+				clkdiv = 0;
+			} else if (clkdiv > 511) {
 				dev_warn(&mmc->class_dev,
 				         "clock %u too slow; using %lu\n",
 				         clock_min, host->bus_hz / (511 + 2));