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From:   Hugo Villeneuve <hugo@hugovil.com>
To:     gregkh@linuxfoundation.org, jirislaby@kernel.org,
        hvilleneuve@dimonoff.com
Cc:     linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
        hugo@hugovil.com, stable@vger.kernel.org,
        Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Thu, 30 Nov 2023 14:10:43 -0500
Message-Id: <20231130191050.3165862-2-hugo@hugovil.com>
In-Reply-To: <20231130191050.3165862-1-hugo@hugovil.com>
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Subject: [PATCH 1/7] serial: sc16is7xx: fix snprintf format specifier in sc16is7xx_regmap_name()
Precedence: bulk

From: Hugo Villeneuve <hvilleneuve@dimonoff.com>

Change snprint format specifier from %d to %u since port_id is unsigned.

Fixes: 3837a0379533 ("serial: sc16is7xx: improve regmap debugfs by using one regmap per port")
Cc: stable@vger.kernel.org # 6.1.x: 3837a03 serial: sc16is7xx: improve regmap debugfs by using one regmap per port
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
---
I did not originally add a "Cc: stable" tag for commit 3837a0379533 ("serial: sc16is7xx: improve regmap debugfs by using one regmap per port")
as it was intended only to improve debugging using debugfs. But
since then, I have been able to confirm that it also fixes a long standing
bug in our system where the Tx interrupt are no longer enabled at some
point when transmitting large RS-485 paquets (> 64 bytes, which is the size
of the FIFO). I have been investigating why, but so far I haven't found the
exact cause, altough I suspect it has something to do with regmap caching.
Therefore, I have added it as a prerequisite for this patch so that it is
automatically added to the stable kernels.
---
 drivers/tty/serial/sc16is7xx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 10e90a7774f0..8e5baf2f6ec6 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1700,7 +1700,7 @@ static const char *sc16is7xx_regmap_name(unsigned int port_id)
 {
 	static char buf[6];
 
-	snprintf(buf, sizeof(buf), "port%d", port_id);
+	snprintf(buf, sizeof(buf), "port%u", port_id);
 
 	return buf;
 }
-- 
2.39.2