[v2] mtd: omap: nand: Remove 0xFF's that prefixed 16bit NAND commands

Message ID 20121026193531.GA21481@harvey-pc.matrox.com
State New, archived
Headers show

Commit Message

Christopher Harvey Oct. 26, 2012, 7:35 p.m.
In 16bit NAND mode the GPMC would send the command 0xNN as 0xFFNN
instead of 0x00NN on the bus. The 0xFFs were actually uninitialized
bits that were left unset in the GPMC command output register. The
reason they weren't initialized in 16bit mode is that if the same code
that writes to this register was used in 8bit mode then 2 commands
would be output in 8bit mode. One for the low byte, and an extra 0x0
command for the high byte. This commit uses writew if we're using
16bit NAND.

Most chips seem fine with the extra 0xFFs, but the ONFI spec says

Signed-off-by: Christopher Harvey <charvey@matrox.com>
 drivers/mtd/nand/omap2.c |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)


diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
index 5b31386..ae6738f 100644
--- a/drivers/mtd/nand/omap2.c
+++ b/drivers/mtd/nand/omap2.c
@@ -225,16 +225,20 @@  static void omap_hwcontrol(struct mtd_info *mtd, int cmd, unsigned int ctrl)
 	struct omap_nand_info *info = container_of(mtd,
 					struct omap_nand_info, mtd);
+	void __iomem *reg;
 	if (cmd != NAND_CMD_NONE) {
 		if (ctrl & NAND_CLE)
-			writeb(cmd, info->reg.gpmc_nand_command);
+			reg = info->reg.gpmc_nand_command;
 		else if (ctrl & NAND_ALE)
-			writeb(cmd, info->reg.gpmc_nand_address);
+			reg = info->reg.gpmc_nand_address;
 		else /* NAND_NCE */
-			writeb(cmd, info->reg.gpmc_nand_data);
+			reg = info->reg.gpmc_nand_data;
+		if (info->nand.options & NAND_BUSWIDTH_16)
+			writew(cmd, reg);
+		else
+			writeb(cmd, reg);