[ARM] 3485/1: i.MX: MX1 SD/MMC fix of unintentional double start possibility

[pandora-kernel.git] / drivers / mmc / imxmmc.c

diff --git a/drivers/mmc/imxmmc.c b/drivers/mmc/imxmmc.c
index ffb7f55..07f36c4 100644 (file)
--- 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);;