mmc: core: Throttle polling rate for CMD6

[linux-2.6-microblaze.git] / drivers / mmc / core / mmc_ops.c

diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index e025604..da424dc 100644 (file)
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -456,6 +456,7 @@ static int mmc_poll_for_busy(struct mmc_card *card, unsigned int timeout_ms,
        struct mmc_host *host = card->host;
        int err;
        unsigned long timeout;
+       unsigned int udelay = 32, udelay_max = 32768;
        u32 status = 0;
        bool expired = false;
        bool busy = false;
@@ -500,6 +501,13 @@ static int mmc_poll_for_busy(struct mmc_card *card, unsigned int timeout_ms,
                                mmc_hostname(host), __func__);
                        return -ETIMEDOUT;
                }
+
+               /* Throttle the polling rate to avoid hogging the CPU. */
+               if (busy) {
+                       usleep_range(udelay, udelay * 2);
+                       if (udelay < udelay_max)
+                               udelay *= 2;
+               }
        } while (busy);
 
        return 0;