mtd: gpmi: initialize the timing registers only one time

The current code initializes the timing registers at very time
we call the gpmi_begin(). This really wastes the cpu cycles.

Add a new flag to let the gpmi driver initializes the timing registers
only one time.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index c036e51..3502acc 100644 (file)
--- a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
@@ -914,6 +914,9 @@ static int enable_edo_mode(struct gpmi_nand_data *this, int mode)
        rate = (mode == 5) ? 100000000 : 80000000;
        clk_set_rate(r->clock[0], rate);
 
+       /* Let the gpmi_begin() re-compute the timing again. */
+       this->flags &= ~GPMI_TIMING_INIT_OK;
+
        this->flags |= GPMI_ASYNC_EDO_ENABLED;
        this->timing_mode = mode;
        dev_info(this->dev, "enable the asynchronous EDO mode %d\n", mode);
@@ -964,6 +967,11 @@ void gpmi_begin(struct gpmi_nand_data *this)
                goto err_out;
        }
 
+       /* Only initialize the timing once */
+       if (this->flags & GPMI_TIMING_INIT_OK)
+               return;
+       this->flags |= GPMI_TIMING_INIT_OK;
+
        if (this->flags & GPMI_ASYNC_EDO_ENABLED)
                gpmi_compute_edo_timing(this, &hw);
        else

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
index 5b6d546..7ac25c1 100644 (file)
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.h
@@ -124,6 +124,7 @@ struct nand_timing {
 struct gpmi_nand_data {
        /* flags */
 #define GPMI_ASYNC_EDO_ENABLED (1 << 0)
+#define GPMI_TIMING_INIT_OK    (1 << 1)
        int                     flags;
 
        /* System Interface */