[PATCH v3 3/3] mtd: cfi_cmdset_0002: Use chip_ready() for write on S29GL064N

[Tokunori Ikegami <ikegami.t@gmail.com>]

As pointed out by this bug report [1], the buffered write is now broken on
S29GL064N. The reason is that changed the buffered write to use chip_good
instead of chip_ready. One way to solve the issue is to revert the change
partially to use chip_ready for S29GL064N since the way of least surprise.

[1] https://lore.kernel.org/r/b687c259-6413-26c9-d4c9-b3afa69ea124@pengutronix.de/

Fixes: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>
Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Vignesh Raghavendra <vigneshr@ti.com>
Cc: linux-mtd@lists.infradead.org
Cc: stable@vger.kernel.org
---
 drivers/mtd/chips/cfi_cmdset_0002.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index 8f3f0309dc03..fa11db066c99 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -867,10 +867,20 @@ static int __xipram chip_good(struct map_info *map, struct flchip *chip,
 	return chip_check(map, chip, addr, &expected);
 }
 
+static bool __xipram cfi_use_chip_ready_for_write(struct map_info *map)
+{
+	struct cfi_private *cfi = map->fldrv_priv;
+
+	return cfi->mfr == CFI_MFR_AMD && cfi->id == S29GL064N_MN12;
+}
+
 static int __xipram chip_good_for_write(struct map_info *map,
 					struct flchip *chip, unsigned long addr,
 					map_word expected)
 {
+	if (cfi_use_chip_ready_for_write(map))
+		return chip_ready(map, chip, addr);
+
 	return chip_good(map, chip, addr, expected);
 }
 
-- 
2.32.0