mtd: gpmi: initialize the timing registers only one time

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=9c95f11b9e743aa6134134a6dcf866a9d5661972
Commit:     9c95f11b9e743aa6134134a6dcf866a9d5661972
Parent:     995fbbf563fcec058a1135bdd112ac969c817e65
Author:     Huang Shijie <b32955 at freescale.com>
AuthorDate: Thu Sep 13 14:58:00 2012 +0800
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Sat Sep 29 15:56:45 2012 +0100

    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 at freescale.com>
    Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/nand/gpmi-nand/gpmi-lib.c  |    8 ++++++++
 drivers/mtd/nand/gpmi-nand/gpmi-nand.h |    1 +
 2 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-lib.c b/drivers/mtd/nand/gpmi-nand/gpmi-lib.c
index c036e51..3502acc 100644
--- 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
--- 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 */