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>

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

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 */