Revert "mtd: atmel_nand: optimize read/write buffer functions"
authorArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Thu, 2 Feb 2012 11:54:25 +0000 (13:54 +0200)
committerDavid Woodhouse <David.Woodhouse@intel.com>
Sat, 4 Feb 2012 08:04:57 +0000 (08:04 +0000)
This reverts commit fb5427508abbd635e877fabdf55795488119c2d6.

The reason is that it breaks 16 bits NAND flash as it was reported by
Nikolaus Voss and confirmed by Eric BĂ©nard.

Nicolas Ferre <nicolas.ferre@atmel.com> alco confirmed:
"After double checking with designers, I must admit that I misunderstood
the way of optimizing accesses to SMC. 16 bit nand is not so common
those days..."

Reported-by: Nikolaus Voss <n.voss@weinmann.de>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org [3.1+]
drivers/mtd/nand/atmel_nand.c

index 4dd056e2e16ac3e6798300e4b1cb13dde0948fb1..35b4fb55dbd6569dad6d4c927c9807698804b882 100644 (file)
@@ -161,6 +161,37 @@ static int atmel_nand_device_ready(struct mtd_info *mtd)
                 !!host->board->rdy_pin_active_low;
 }
 
+/*
+ * Minimal-overhead PIO for data access.
+ */
+static void atmel_read_buf8(struct mtd_info *mtd, u8 *buf, int len)
+{
+       struct nand_chip        *nand_chip = mtd->priv;
+
+       __raw_readsb(nand_chip->IO_ADDR_R, buf, len);
+}
+
+static void atmel_read_buf16(struct mtd_info *mtd, u8 *buf, int len)
+{
+       struct nand_chip        *nand_chip = mtd->priv;
+
+       __raw_readsw(nand_chip->IO_ADDR_R, buf, len / 2);
+}
+
+static void atmel_write_buf8(struct mtd_info *mtd, const u8 *buf, int len)
+{
+       struct nand_chip        *nand_chip = mtd->priv;
+
+       __raw_writesb(nand_chip->IO_ADDR_W, buf, len);
+}
+
+static void atmel_write_buf16(struct mtd_info *mtd, const u8 *buf, int len)
+{
+       struct nand_chip        *nand_chip = mtd->priv;
+
+       __raw_writesw(nand_chip->IO_ADDR_W, buf, len / 2);
+}
+
 static void dma_complete_func(void *completion)
 {
        complete(completion);
@@ -235,27 +266,33 @@ err_buf:
 static void atmel_read_buf(struct mtd_info *mtd, u8 *buf, int len)
 {
        struct nand_chip *chip = mtd->priv;
+       struct atmel_nand_host *host = chip->priv;
 
        if (use_dma && len > mtd->oobsize)
                /* only use DMA for bigger than oob size: better performances */
                if (atmel_nand_dma_op(mtd, buf, len, 1) == 0)
                        return;
 
-       /* if no DMA operation possible, use PIO */
-       memcpy_fromio(buf, chip->IO_ADDR_R, len);
+       if (host->board->bus_width_16)
+               atmel_read_buf16(mtd, buf, len);
+       else
+               atmel_read_buf8(mtd, buf, len);
 }
 
 static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
 {
        struct nand_chip *chip = mtd->priv;
+       struct atmel_nand_host *host = chip->priv;
 
        if (use_dma && len > mtd->oobsize)
                /* only use DMA for bigger than oob size: better performances */
                if (atmel_nand_dma_op(mtd, (void *)buf, len, 0) == 0)
                        return;
 
-       /* if no DMA operation possible, use PIO */
-       memcpy_toio(chip->IO_ADDR_W, buf, len);
+       if (host->board->bus_width_16)
+               atmel_write_buf16(mtd, buf, len);
+       else
+               atmel_write_buf8(mtd, buf, len);
 }
 
 /*