[PATCH v8 5/7] omap3: nand: configurable fifo threshold to gain the throughput
Sukumar Ghorai
s-ghorai at ti.com
Tue Jan 4 08:33:22 EST 2011
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 at ti.com>
Signed-off-by: Sukumar Ghorai <s-ghorai at ti.com>
---
arch/arm/mach-omap2/gpmc.c | 11 +++++++----
arch/arm/plat-omap/include/plat/gpmc.h | 5 ++++-
drivers/mtd/nand/omap2.c | 22 ++++++++++++++--------
3 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/arch/arm/mach-omap2/gpmc.c b/arch/arm/mach-omap2/gpmc.c
index a2df8b1..117ab29 100644
--- a/arch/arm/mach-omap2/gpmc.c
+++ b/arch/arm/mach-omap2/gpmc.c
@@ -59,7 +59,6 @@
#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
@@ -595,15 +594,19 @@ 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);
@@ -611,7 +614,7 @@ 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 054e704..9e4dc7a 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, while
* the register values are in gpmc_fck cycles.
@@ -133,7 +136,7 @@ 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 fbe8414..f1648fd 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;
--
1.7.0.4
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