omap3: nand: configurable fifo threshold to gain the throughput

Configure the FIFO THREASHOLD value different for read and write to keep busy
both filling and to drain out of FIFO at reading and writing.

Signed-off-by: Vimal Singh <vimalsingh@ti.com>
Signed-off-by: Sukumar Ghorai <s-ghorai@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index 382dea83e4f0..674174365f78 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -60,7 +60,6 @@
 #define GPMC_CHUNK_SHIFT        24              /* 16 MB */
 #define GPMC_SECTION_SHIFT      28              /* 128 MB */
 
-#define PREFETCH_FIFOTHRESHOLD  (0x40 << 8)
 #define CS_NUM_SHIFT            24
 #define ENABLE_PREFETCH         (0x1 << 7)
 #define DMA_MPU_MODE            2
@@ -606,15 +605,19 @@ EXPORT_SYMBOL(gpmc_nand_write);
 /**
  * gpmc_prefetch_enable - configures and starts prefetch transfer
  * @cs: cs (chip select) number
+ * @fifo_th: fifo threshold to be used for read/ write
  * @dma_mode: dma mode enable (1) or disable (0)
  * @u32_count: number of bytes to be transferred
  * @is_write: prefetch read(0) or write post(1) mode
  */
-int gpmc_prefetch_enable(int cs, int dma_mode,
+int gpmc_prefetch_enable(int cs, int fifo_th, int dma_mode,
                                 unsigned int u32_count, int is_write)
 {
 
-        if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
+        if (fifo_th > PREFETCH_FIFOTHRESHOLD_MAX) {
+                pr_err("gpmc: fifo threshold is not supported\n");
+                return -1;
+        } else if (!(gpmc_read_reg(GPMC_PREFETCH_CONTROL))) {
                 /* Set the amount of bytes to be prefetched */
                 gpmc_write_reg(GPMC_PREFETCH_CONFIG2, u32_count);
 
@@ -622,7 +625,7 @@ int gpmc_prefetch_enable(int cs, int dma_mode,
                  * enable the engine. Set which cs is has requested for.
                  */
                 gpmc_write_reg(GPMC_PREFETCH_CONFIG1, ((cs << CS_NUM_SHIFT) |
-                                        PREFETCH_FIFOTHRESHOLD |
+                                        PREFETCH_FIFOTHRESHOLD(fifo_th) |
                                         ENABLE_PREFETCH |
                                         (dma_mode << DMA_MPU_MODE) |
                                         (0x1 & is_write)));