From e45a4b652dbd2f8b5a3b8e97e89f602a58cb28aa Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Mon, 18 May 2020 17:52:37 +0200
Subject: [PATCH] mtd: rawnand: Fix nand_gpio_waitrdy()
Git-commit: e45a4b652dbd2f8b5a3b8e97e89f602a58cb28aa
Patch-mainline: v5.8-rc1
References: git-fixes

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
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/mtd/nand/raw/nand_base.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index c4d6d5482b31..79e8052bdff9 100644
--- 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;
-- 
2.16.4