[PATCH v6 15/18] mtd: nand: denali: skip driver internal bounce buffer when possible

[Masahiro Yamada]

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.masah...@socionext.com>
---

Changes in v6: None
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 1ded7cc00b1a..918b9b9bbe53 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -592,12 +592,16 @@ 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) {
                /*
@@ -628,7 +632,7 @@ 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);
 
        if (irq_status & INTR__ERASED_PAGE)
                memset(buf, 0xff, size);
@@ -814,12 +818,10 @@ 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)
@@ -923,10 +925,8 @@ 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)
@@ -1365,14 +1365,8 @@ 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;
        }
 
        /*
@@ -1462,16 +1456,8 @@ 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