mtd: nand: allow NAND_NO_SUBPAGE_WRITE to be set from driver

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.

Note, this patch fixes some major gpmi-nand breakage.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Tested-by: Huang Shijie <shijie8@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

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

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