1 files changed, 43 insertions, 11 deletions

diff --git a/drivers/mmc/imxmmc.c b/drivers/mmc/imxmmc.c
index ffb7f55d3467..07f36c454bd6 100644
--- a/drivers/mmc/imxmmc.c
+++ b/drivers/mmc/imxmmc.c
@@ -102,6 +102,7 @@ struct imxmci_host {
 #define IMXMCI_PEND_CPU_DATA_b  5
 #define IMXMCI_PEND_CARD_XCHG_b 6
 #define IMXMCI_PEND_SET_INIT_b  7
+#define IMXMCI_PEND_STARTED_b   8
 
 #define IMXMCI_PEND_IRQ_m       (1 << IMXMCI_PEND_IRQ_b)
 #define IMXMCI_PEND_DMA_END_m   (1 << IMXMCI_PEND_DMA_END_b)
@@ -111,6 +112,7 @@ struct imxmci_host {
 #define IMXMCI_PEND_CPU_DATA_m  (1 << IMXMCI_PEND_CPU_DATA_b)
 #define IMXMCI_PEND_CARD_XCHG_m (1 << IMXMCI_PEND_CARD_XCHG_b)
 #define IMXMCI_PEND_SET_INIT_m  (1 << IMXMCI_PEND_SET_INIT_b)
+#define IMXMCI_PEND_STARTED_m   (1 << IMXMCI_PEND_STARTED_b)
 
 static void imxmci_stop_clock(struct imxmci_host *host)
 {
@@ -131,23 +133,52 @@ static void imxmci_stop_clock(struct imxmci_host *host)
         dev_dbg(mmc_dev(host->mmc), "imxmci_stop_clock blocked, no luck\n");
 }
 
-static void imxmci_start_clock(struct imxmci_host *host)
+static int imxmci_start_clock(struct imxmci_host *host)
 {
-        int i = 0;
+        unsigned int trials = 0;
+        unsigned int delay_limit = 128;
+        unsigned long flags;
+
         MMC_STR_STP_CLK &= ~STR_STP_CLK_STOP_CLK;
-        while(i < 0x1000) {
-                if(!(i & 0x7f))
-                        MMC_STR_STP_CLK |= STR_STP_CLK_START_CLK;
 
-                if(MMC_STATUS & STATUS_CARD_BUS_CLK_RUN) {
-                        /* Check twice before cut */
+        clear_bit(IMXMCI_PEND_STARTED_b, &host->pending_events);
+
+        /*
+         * Command start of the clock, this usually succeeds in less
+         * then 6 delay loops, but during card detection (low clockrate)
+         * it takes up to 5000 delay loops and sometimes fails for the first time
+         */
+        MMC_STR_STP_CLK |= STR_STP_CLK_START_CLK;
+
+        do {
+                unsigned int delay = delay_limit;
+
+                while(delay--){
                         if(MMC_STATUS & STATUS_CARD_BUS_CLK_RUN)
-                                return;
+                                /* Check twice before cut */
+                                if(MMC_STATUS & STATUS_CARD_BUS_CLK_RUN)
+                                        return 0;
+
+                        if(test_bit(IMXMCI_PEND_STARTED_b, &host->pending_events))
+                                return 0;
                 }
 
-                i++;
-        }
-        dev_dbg(mmc_dev(host->mmc), "imxmci_start_clock blocked, no luck\n");
+                local_irq_save(flags);
+                /*
+                 * Ensure, that request is not doubled under all possible circumstances.
+                 * It is possible, that cock running state is missed, because some other
+                 * IRQ or schedule delays this function execution and the clocks has
+                 * been already stopped by other means (response processing, SDHC HW)
+                 */
+                if(!test_bit(IMXMCI_PEND_STARTED_b, &host->pending_events))
+                        MMC_STR_STP_CLK |= STR_STP_CLK_START_CLK;
+                local_irq_restore(flags);
+
+        } while(++trials<256);
+
+        dev_err(mmc_dev(host->mmc), "imxmci_start_clock blocked, no luck\n");
+
+        return -1;
 }
 
 static void imxmci_softreset(void)
@@ -622,6 +653,7 @@ static irqreturn_t imxmci_irq(int irq, void *devid, struct pt_regs *regs)
         atomic_set(&host->stuck_timeout, 0);
         host->status_reg = stat;
         set_bit(IMXMCI_PEND_IRQ_b, &host->pending_events);
+        set_bit(IMXMCI_PEND_STARTED_b, &host->pending_events);
         tasklet_schedule(&host->tasklet);
 
         return IRQ_RETVAL(handled);;