mmc: tmio: prevent endless loop in tmio_mmc_set_clock()

I spent a couple of days with the driver just hanging due to me forgetting to
specify the external crystal frequency,  so that clk_get_rate() returned 0 and
thus the loop in tmio_mmc_set_clock() never ended. I don't think that's an
acceptable behavior, so I suggest that the minimum frequency is checked for 0
in tmio_mmc_host_probe().

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Ian Molton <ian.molton@codethink.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
index 692e578cf4d71b306404efeb7f733195b00a1697..e487ba4bb01a746f384dba0ed9fce9f8dda4fc16 100644 (file)
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -1121,6 +1121,15 @@ int tmio_mmc_host_probe(struct tmio_mmc_host **host,
                mmc->f_min = mmc->f_max / 512;
        }
 
+       /*
+        * Check the sanity of mmc->f_min to prevent tmio_mmc_set_clock() from
+        * looping forever...
+        */
+       if (mmc->f_min == 0) {
+               ret = -EINVAL;
+               goto host_free;
+       }
+
        /*
         * While using internal tmio hardware logic for card detection, we need
         * to ensure it stays powered for it to work.