[PATCH v5 21/23] mtd: nand: denali: skip driver internal bounce buffer when possible

Masahiro Yamada
2017-06-07T11:54:05Z

For ecc->read_page() and ecc->write_page(), it is possible to call
dma_map_single() against the given buffer. This bypasses the driver
internal bounce buffer and save the memcpy().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v5: None
Changes in v4:
- Remove dma_unmap_single() from denali_remove()

Changes in v3:
- Set chip->buf_align to 16

Changes in v2:
- Newly added

drivers/mtd/nand/denali.c | 38 ++++++++++++--------------------------
1 file changed, 12 insertions(+), 26 deletions(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 90c702b9f14c..963638693850 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -643,12 +643,16 @@ static int denali_pio_xfer(struct denali_nand_info *denali, void *buf,
static int denali_dma_xfer(struct denali_nand_info *denali, void *buf,
size_t size, int page, int raw, int write)
{
- dma_addr_t dma_addr = denali->dma_addr;
+ dma_addr_t dma_addr;
uint32_t irq_mask, irq_status, ecc_err_mask;
enum dma_data_direction dir = write ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
int ret = 0;

- dma_sync_single_for_device(denali->dev, dma_addr, size, dir);
+ dma_addr = dma_map_single(denali->dev, buf, size, dir);
+ if (dma_mapping_error(denali->dev, dma_addr)) {
+ dev_dbg(denali->dev, "Failed to DMA-map buffer. Trying PIO.\n");
+ return denali_pio_xfer(denali, buf, size, page, raw, write);
+ }

if (write) {
irq_mask = INTR__DMA_CMD_COMP | INTR__PROGRAM_FAIL;
@@ -674,7 +678,7 @@ static int denali_dma_xfer(struct denali_nand_info *denali, void *buf,
ret = -EBADMSG;

denali_enable_dma(denali, false);
- dma_sync_single_for_cpu(denali->dev, dma_addr, size, dir);
+ dma_unmap_single(denali->dev, dma_addr, size, dir);

return ret;
}
@@ -857,12 +861,10 @@ static int denali_read_page(struct mtd_info *mtd, struct nand_chip *chip,
int stat = 0;
int ret;

- ret = denali_data_xfer(denali, denali->buf, mtd->writesize, page, 0, 0);
+ ret = denali_data_xfer(denali, buf, mtd->writesize, page, 0, 0);
if (ret && ret != -EBADMSG)
return ret;

- memcpy(buf, denali->buf, mtd->writesize);
-
if (denali->caps & DENALI_CAP_HW_ECC_FIXUP)
stat = denali_hw_ecc_fixup(mtd, denali, &uncor_ecc_flags);
else if (ret == -EBADMSG)
@@ -966,10 +968,8 @@ static int denali_write_page(struct mtd_info *mtd, struct nand_chip *chip,
{
struct denali_nand_info *denali = mtd_to_denali(mtd);

- memcpy(denali->buf, buf, mtd->writesize);
-
- return denali_data_xfer(denali, denali->buf, mtd->writesize, page,
- 0, 1);
+ return denali_data_xfer(denali, (void *)buf, mtd->writesize,
+ page, 0, 1);
}

static void denali_select_chip(struct mtd_info *mtd, int chip)
@@ -1408,14 +1408,8 @@ int denali_init(struct denali_nand_info *denali)
}

if (denali->dma_avail) {
- denali->dma_addr = dma_map_single(denali->dev, denali->buf,
- mtd->writesize + mtd->oobsize,
- DMA_BIDIRECTIONAL);
- if (dma_mapping_error(denali->dev, denali->dma_addr)) {
- dev_info(denali->dev,
- "Failed to map DMA buffer. Disabling DMA.\n");
- denali->dma_avail = 0;
- };
+ chip->options |= NAND_USE_BOUNCE_BUFFER;
+ chip->buf_align = 16;
}

/*
@@ -1505,16 +1499,8 @@ EXPORT_SYMBOL(denali_init);
void denali_remove(struct denali_nand_info *denali)
{
struct mtd_info *mtd = nand_to_mtd(&denali->nand);
- /*
- * Pre-compute DMA buffer size to avoid any problems in case
- * nand_release() ever changes in a way that mtd->writesize and
- * mtd->oobsize are not reliable after this call.
- */
- int bufsize = mtd->writesize + mtd->oobsize;

nand_release(mtd);
denali_disable_irq(denali);
- dma_unmap_single(denali->dev, denali->dma_addr, bufsize,
- DMA_BIDIRECTIONAL);
}
EXPORT_SYMBOL(denali_remove);
--
2.7.4