[PATCH] mtd: nand: allow NAND_NO_SUBPAGE_WRITE to be set from driver

[Brian Norris <computersforpeace@gmail.com>]

The NAND_CHIPOPTIONS_MSK has limited utility and is causing real bugs. It
silently masks off at least one flag that might be set by the driver
(NAND_NO_SUBPAGE_WRITE). This breaks the GPMI NAND driver and possibly
others.

Really, as long as driver writers exercise a small amount of care with
NAND_* options, this mask is not necessary at all; it was only here to
prevent certain options from accidentally being set by the driver. But the
original thought turns out to be a bad idea occasionally. Thus, kill it.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Cc: Huang Shijie <shijie8@gmail.com>
Cc: Marek Vasut <marex@denx.de>
---
Huang, please test this with your driver.

Artem,

If this is acceptable, should it go to -stable, since it fixes some major
gpmi-nand breakage? It probably won't apply directly, since I've touched some
code around it recently.

 drivers/mtd/nand/nand_base.c | 7 ++-----
 include/linux/mtd/nand.h     | 3 ---
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 98ba46e..6652d1f 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2909,8 +2909,6 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 	if (le16_to_cpu(p->features) & 1)
 		*busw = NAND_BUSWIDTH_16;
 
-	chip->options &= ~NAND_CHIPOPTIONS_MSK;
-
 	pr_info("ONFI flash detected\n");
 	return 1;
 }
@@ -3074,9 +3072,8 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
 			mtd->erasesize <<= ((id_data[3] & 0x03) << 1);
 		}
 	}
-	/* Get chip options, preserve non chip based options */
-	chip->options &= ~NAND_CHIPOPTIONS_MSK;
-	chip->options |= type->options & NAND_CHIPOPTIONS_MSK;
+	/* Get chip options */
+	chip->options |= type->options;
 
 	/*
 	 * Check if chip is not a Samsung device. Do not clear the
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 6dce5a7..eeb7015 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -206,9 +206,6 @@ typedef enum {
 #define NAND_SUBPAGE_READ(chip) ((chip->ecc.mode == NAND_ECC_SOFT) \
 					&& (chip->page_shift > 9))
 
-/* Mask to zero out the chip options, which come from the id table */
-#define NAND_CHIPOPTIONS_MSK	0x0000ffff
-
 /* Non chip related options */
 /* This option skips the bbt scan during initialization. */
 #define NAND_SKIP_BBTSCAN	0x00010000
-- 
1.7.11.1