As reported by the OpenWRT team, write requests sometimes fail on some platforms. Currently to check the state chip_ready() is used correctly as described by the flash memory S29GL256P11TFI01 datasheet. Also chip_good() is used to check if the write is succeeded and it was implemented by the commit fb4a90bfcd6d8 ("[MTD] CFI-0002 - Improve error checking"). But actually the write failure is caused on some platforms and also it can be fixed by using chip_good() to check the state and retry instead. Also it seems that it is caused after repeated about 1,000 times to retry the write one word with the reset command. By using chip_good() to check the state to be done it can be reduced the retry with reset. It is depended on the actual flash chip behavior so the root cause is unknown.

Cc: Chris Packham chris.packham@alliedtelesis.co.nz Cc: Joakim Tjernlund Joakim.Tjernlund@infinera.com Cc: linux-mtd@lists.infradead.org Cc: stable@vger.kernel.org Reported-by: Fabio Bettoni fbettoni@gmail.com Signed-off-by: Felix Fietkau nbd@nbd.name Signed-off-by: Hauke Mehrtens hauke@hauke-m.de Signed-off-by: Tokunori Ikegami ikegami.t@gmail.com [vigneshr@ti.com: Fix a checkpatch warning] Signed-off-by: Vignesh Raghavendra vigneshr@ti.com --- drivers/mtd/chips/cfi_cmdset_0002.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c index af3d207c9cc4..e773dc6fdd3c 100644 --- a/drivers/mtd/chips/cfi_cmdset_0002.c +++ b/drivers/mtd/chips/cfi_cmdset_0002.c @@ -1628,29 +1628,35 @@ static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip, continue; }

- if (time_after(jiffies, timeo) && !chip_ready(map, adr)){ + /* + * We check "time_after" and "!chip_good" before checking + * "chip_good" to avoid the failure due to scheduling. + */ + if (time_after(jiffies, timeo) && !chip_good(map, adr, datum)) { xip_enable(map, chip, adr); printk(KERN_WARNING "MTD %s(): software timeout\n", __func__); xip_disable(map, chip, adr); + ret = -EIO; break; }

- if (chip_ready(map, adr)) + if (chip_good(map, adr, datum)) break;

/* Latency issues. Drop the lock, wait a while and retry */ UDELAY(map, chip, adr, 1); } + /* Did we succeed? */ - if (!chip_good(map, adr, datum)) { + if (ret) { /* reset on all failures. */ map_write( map, CMD(0xF0), chip->start ); /* FIXME - should have reset delay before continuing */

- if (++retry_cnt <= MAX_RETRIES) + if (++retry_cnt <= MAX_RETRIES) { + ret = 0; goto retry; - - ret = -EIO; + } } xip_enable(map, chip, adr); op_done: