[U-Boot] [PATCH v2 2/8] mtd: vf610_nfc: remove read on SEQIN

[Stefan Agner]

Since we do not support sub-page writes anyway, reading the page
back to the controller on SEQIN command is not required. Remove
the page read on SEQIN.

However, the column/page values relevant to the SEQIN command, hence
set the column/row address on SEQIN command.

Signed-off-by: Stefan Agner <stefan at agner.ch>
---
This improved the write performance quite nicely. The nand write
command improves from 2.9MiB/s to 3.5MiB/s. A ubi write of a UBIFS
image which is around 100MiB improves from 34.5s to 27.1s. Measured
on a Colibri VF61 (512MiB Macronix NAND).

 drivers/mtd/nand/vf610_nfc.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
index fa0bb9d..66b335d 100644
--- a/drivers/mtd/nand/vf610_nfc.c
+++ b/drivers/mtd/nand/vf610_nfc.c
@@ -345,24 +345,26 @@ static void vf610_nfc_command(struct mtd_info *mtd, unsigned command,
 	nfc->alt_buf	= 0;
 
 	switch (command) {
+	case NAND_CMD_SEQIN:
+		/* Use valid column/page from preread... */
+		vf610_nfc_addr_cycle(mtd, column, page);
+		/*
+		 * SEQIN => data => PAGEPROG sequence is done by the controller
+		 * hence we do not need to issue the command here...
+		 */
+		return;
 	case NAND_CMD_PAGEPROG:
 		vf610_nfc_transfer_size(nfc->regs, nfc->page_sz);
 		vf610_nfc_send_commands(nfc->regs, NAND_CMD_SEQIN,
 					command, PROGRAM_PAGE_CMD_CODE);
-		vf610_nfc_addr_cycle(mtd, column, page);
 		break;
 
 	case NAND_CMD_RESET:
 		vf610_nfc_transfer_size(nfc->regs, 0);
 		vf610_nfc_send_command(nfc->regs, command, RESET_CMD_CODE);
 		break;
-	/*
-	 * NFC does not support sub-page reads and writes,
-	 * so emulate them using full page transfers.
-	 */
 	case NAND_CMD_READOOB:
 		nfc->spareonly = 1;
-	case NAND_CMD_SEQIN: /* Pre-read for partial writes. */
 	case NAND_CMD_READ0:
 		column = 0;
 		vf610_nfc_transfer_size(nfc->regs, nfc->page_sz);
-- 
2.3.5