3 files changed, 25 insertions, 13 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)));
diff --git a/arch/arm/plat-omap/include/plat/gpmc.h b/arch/arm/plat-omap/include/plat/gpmc.h
index 9c060da0a873..a2434639063d 100644
--- a/arch/arm/plat-omap/include/plat/gpmc.h
+++ b/arch/arm/plat-omap/include/plat/gpmc.h
@@ -83,6 +83,9 @@
 #define GPMC_IRQ_FIFOEVENTENABLE        0x01
 #define GPMC_IRQ_COUNT_EVENT            0x02
 
+#define PREFETCH_FIFOTHRESHOLD_MAX      0x40
+#define PREFETCH_FIFOTHRESHOLD(val)     ((val) << 8)
+
 /*
  * Note that all values in this struct are in nanoseconds except sync_clk
  * (which is in picoseconds), while the register values are in gpmc_fck cycles.
@@ -134,7 +137,7 @@ extern int gpmc_cs_request(int cs, unsigned long size, unsigned long *base);
 extern void gpmc_cs_free(int cs);
 extern int gpmc_cs_set_reserved(int cs, int reserved);
 extern int gpmc_cs_reserved(int cs);
-extern int gpmc_prefetch_enable(int cs, int dma_mode,
+extern int gpmc_prefetch_enable(int cs, int fifo_th, int dma_mode,
                                         unsigned int u32_count, int is_write);
 extern int gpmc_prefetch_reset(int cs);
 extern void omap3_gpmc_save_context(void);
diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index fbe841467175..f1648fd5924a 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -244,7 +244,8 @@ static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
         }
 
         /* configure and start prefetch transfer */
-        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
+        ret = gpmc_prefetch_enable(info->gpmc_cs,
+                        PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x0);
         if (ret) {
                 /* PFPW engine is busy, use cpu copy method */
                 if (info->nand.options & NAND_BUSWIDTH_16)
@@ -289,7 +290,8 @@ static void omap_write_buf_pref(struct mtd_info *mtd,
         }
 
         /*  configure and start prefetch transfer */
-        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
+        ret = gpmc_prefetch_enable(info->gpmc_cs,
+                        PREFETCH_FIFOTHRESHOLD_MAX, 0x0, len, 0x1);
         if (ret) {
                 /* PFPW engine is busy, use cpu copy method */
                 if (info->nand.options & NAND_BUSWIDTH_16)
@@ -345,8 +347,9 @@ static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
         int ret;
         unsigned long tim, limit;
 
-        /* The fifo depth is 64 bytes. We have a sync at each frame and frame
-         * length is 64 bytes.
+        /* The fifo depth is 64 bytes max.
+         * But configure the FIFO-threahold to 32 to get a sync at each frame
+         * and frame length is 32 bytes.
          */
         int buf_len = len >> 6;
 
@@ -387,7 +390,8 @@ static inline int omap_nand_dma_transfer(struct mtd_info *mtd, void *addr,
                                         OMAP24XX_DMA_GPMC, OMAP_DMA_SRC_SYNC);
         }
         /*  configure and start prefetch transfer */
-        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x1, len, is_write);
+        ret = gpmc_prefetch_enable(info->gpmc_cs,
+                        PREFETCH_FIFOTHRESHOLD_MAX, 0x1, len, is_write);
         if (ret)
                 /* PFPW engine is busy, use cpu copy method */
                 goto out_copy;
@@ -522,7 +526,8 @@ static void omap_read_buf_irq_pref(struct mtd_info *mtd, u_char *buf, int len)
         init_completion(&info->comp);
 
         /*  configure and start prefetch transfer */
-        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
+        ret = gpmc_prefetch_enable(info->gpmc_cs,
+                        PREFETCH_FIFOTHRESHOLD_MAX/2, 0x0, len, 0x0);
         if (ret)
                 /* PFPW engine is busy, use cpu copy method */
                 goto out_copy;
@@ -569,8 +574,9 @@ static void omap_write_buf_irq_pref(struct mtd_info *mtd,
         info->buf = (u_char *) buf;
         init_completion(&info->comp);
 
-        /*  configure and start prefetch transfer */
-        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x1);
+        /* configure and start prefetch transfer : size=24 */
+        ret = gpmc_prefetch_enable(info->gpmc_cs,
+                        (PREFETCH_FIFOTHRESHOLD_MAX * 3) / 8, 0x0, len, 0x1);
         if (ret)
                 /* PFPW engine is busy, use cpu copy method */
                 goto out_copy;