[PATCH v4 2/3] 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], buffered writes are now broken on
S29GL064N. This issue comes from a rework which switched from using chip_good()
to chip_ready(), because DQ true data 0xFF is read on S29GL064N and an error
returned by chip_good(). One way to solve the issue is to revert the change
partially to use chip_ready for S29GL064N.

[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: stable@vger.kernel.org
---
 drivers/mtd/chips/cfi_cmdset_0002.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
index e68ddf0f7fc0..6c57f85e1b8e 100644
--- a/drivers/mtd/chips/cfi_cmdset_0002.c
+++ b/drivers/mtd/chips/cfi_cmdset_0002.c
@@ -866,6 +866,23 @@ static int __xipram chip_check(struct map_info *map, struct flchip *chip,
 		chip_check(map, chip, addr, &datum); \
 	})
 
+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 == 0x0c01;
+}
+
+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);
+}
+
 static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode)
 {
 	DECLARE_WAITQUEUE(wait, current);
@@ -1686,7 +1703,7 @@ static int __xipram do_write_oneword_once(struct map_info *map,
 		 * "chip_good" to avoid the failure due to scheduling.
 		 */
 		if (time_after(jiffies, timeo) &&
-		    !chip_good(map, chip, adr, datum)) {
+		    !chip_good_for_write(map, chip, adr, datum)) {
 			xip_enable(map, chip, adr);
 			printk(KERN_WARNING "MTD %s(): software timeout\n", __func__);
 			xip_disable(map, chip, adr);
@@ -1694,7 +1711,7 @@ static int __xipram do_write_oneword_once(struct map_info *map,
 			break;
 		}
 
-		if (chip_good(map, chip, adr, datum)) {
+		if (chip_good_for_write(map, chip, adr, datum)) {
 			if (cfi_check_err_status(map, chip, adr))
 				ret = -EIO;
 			break;
@@ -1966,14 +1983,14 @@ static int __xipram do_write_buffer_wait(struct map_info *map,
 		 * "chip_good" to avoid the failure due to scheduling.
 		 */
 		if (time_after(jiffies, timeo) &&
-		    !chip_good(map, chip, adr, datum)) {
+		    !chip_good_for_write(map, chip, adr, datum)) {
 			pr_err("MTD %s(): software timeout, address:0x%.8lx.\n",
 			       __func__, adr);
 			ret = -EIO;
 			break;
 		}
 
-		if (chip_good(map, chip, adr, datum)) {
+		if (chip_good_for_write(map, chip, adr, datum)) {
 			if (cfi_check_err_status(map, chip, adr))
 				ret = -EIO;
 			break;
-- 
2.32.0