linux-kernel - [PATCH v4 2/5] mtd: rawnand: brcmnand: Fix potential false time out warning

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Message-Id: <20230706182909.79151-3-william.zhang@broadcom.com>
Date:   Thu,  6 Jul 2023 11:29:06 -0700
From:   William Zhang <william.zhang@...adcom.com>
To:     Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>,
        Linux MTD List <linux-mtd@...ts.infradead.org>
Cc:     f.fainelli@...il.com, rafal@...ecki.pl, kursad.oney@...adcom.com,
        joel.peshkin@...adcom.com, computersforpeace@...il.com,
        anand.gore@...adcom.com, dregan@...l.com, kamal.dasu@...adcom.com,
        tomer.yacoby@...adcom.com, dan.beygelman@...adcom.com,
        William Zhang <william.zhang@...adcom.com>,
        Florian Fainelli <florian.fainelli@...adcom.com>,
        stable@...r.kernel.org, Miquel Raynal <miquel.raynal@...tlin.com>,
        linux-kernel@...r.kernel.org,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Boris Brezillon <bbrezillon@...nel.org>,
        Kamal Dasu <kdasu.kdev@...il.com>
Subject: [PATCH v4 2/5] mtd: rawnand: brcmnand: Fix potential false time out warning

If system is busy during the command status polling function, the driver
may not get the chance to poll the status register till the end of time
out and return the premature status.  Do a final check after time out
happens to ensure reading the correct status.

Fixes: 9d2ee0a60b8b ("mtd: nand: brcmnand: Check flash #WP pin status before nand erase/program")
Signed-off-by: William Zhang <william.zhang@...adcom.com>
Reviewed-by: Florian Fainelli <florian.fainelli@...adcom.com>
Cc: stable@...r.kernel.org

---

Changes in v4:
- Update comment in the polling status function
- Add cc stable tag

Changes in v3: None
Changes in v2: None

 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index 9ea96911d16b..9a373a10304d 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -1080,6 +1080,14 @@ static int bcmnand_ctrl_poll_status(struct brcmnand_controller *ctrl,
 		cpu_relax();
 	} while (time_after(limit, jiffies));
 
+	/*
+	 * do a final check after time out in case the CPU was busy and the driver
+	 * did not get enough time to perform the polling to avoid false alarms
+	 */
+	val = brcmnand_read_reg(ctrl, BRCMNAND_INTFC_STATUS);
+	if ((val & mask) == expected_val)
+		return 0;
+
 	dev_warn(ctrl->dev, "timeout on status poll (expected %x got %x)\n",
 		 expected_val, val & mask);
 
-- 
2.37.3


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