MMC core: limit minimum initialization frequency to 400kHz

Some controllers allow a much lower frequency than 400kHz.
Keep the minimum frequency within sensible limits.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 23fb2c39d9ed..d84c880fac84 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -708,7 +708,13 @@ static void mmc_power_up(struct mmc_host *host)
          */
         mmc_delay(10);
 
-        host->ios.clock = host->f_min;
+        if (host->f_min > 400000) {
+                pr_warning("%s: Minimum clock frequency too high for "
+                                "identification mode\n", mmc_hostname(host));
+                host->ios.clock = host->f_min;
+        } else
+                host->ios.clock = 400000;
+
         host->ios.power_mode = MMC_POWER_ON;
         mmc_set_ios(host);