mtd: rawnand: Fix nand_gpio_waitrdy()

Mimic what's done in nand_soft_waitrdy() and add one to the jiffies
timeout so we don't end up waiting less than actually required.

Reported-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Fixes: b0e137ad24b6c ("mtd: rawnand: Provide helper for polling GPIO R/B pin")
Cc: <stable@vger.kernel.org>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200518155237.297549-1-boris.brezillon@collabora.com

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index c4d6d54..79e8052 100644 (file)
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -790,8 +790,14 @@ EXPORT_SYMBOL_GPL(nand_soft_waitrdy);
 int nand_gpio_waitrdy(struct nand_chip *chip, struct gpio_desc *gpiod,
                      unsigned long timeout_ms)
 {
-       /* Wait until R/B pin indicates chip is ready or timeout occurs */
-       timeout_ms = jiffies + msecs_to_jiffies(timeout_ms);
+
+       /*
+        * Wait until R/B pin indicates chip is ready or timeout occurs.
+        * +1 below is necessary because if we are now in the last fraction
+        * of jiffy and msecs_to_jiffies is 1 then we will wait only that
+        * small jiffy fraction - possibly leading to false timeout.
+        */
+       timeout_ms = jiffies + msecs_to_jiffies(timeout_ms) + 1;
        do {
                if (gpiod_get_value_cansleep(gpiod))
                        return 0;