linux-kernel - [PATCH v2 03/16] serial: sc16is7xx: set safe default SPI clock frequency

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Message-Id: <20231221231823.2327894-4-hugo@hugovil.com>
Date: Thu, 21 Dec 2023 18:18:10 -0500
From: Hugo Villeneuve <hugo@...ovil.com>
To: gregkh@...uxfoundation.org,
	jirislaby@...nel.org,
	kubakici@...pl,
	indrakanti_ram@...mail.com,
	phil@...pberrypi.org
Cc: linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	hugo@...ovil.com,
	Hugo Villeneuve <hvilleneuve@...onoff.com>,
	stable@...r.kernel.org
Subject: [PATCH v2 03/16] serial: sc16is7xx: set safe default SPI clock frequency

From: Hugo Villeneuve <hvilleneuve@...onoff.com>

15 MHz is supported only by 76x variants.

If the SPI clock frequency is not specified, use a safe default clock value
of 4 MHz that is supported by all variants.

Also use HZ_PER_MHZ macro to improve readability.

Fixes: 2c837a8a8f9f ("sc16is7xx: spi interface is added")
Cc: stable@...r.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
---
 drivers/tty/serial/sc16is7xx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 798fa115b28a..ced2446909a2 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -24,6 +24,7 @@
 #include <linux/tty_flip.h>
 #include <linux/spi/spi.h>
 #include <linux/uaccess.h>
+#include <linux/units.h>
 #include <uapi/linux/sched/types.h>
 
 #define SC16IS7XX_NAME			"sc16is7xx"
@@ -1738,7 +1739,7 @@ static int sc16is7xx_spi_probe(struct spi_device *spi)
 		return dev_err_probe(&spi->dev, -EINVAL, "Unsupported SPI mode\n");
 
 	spi->mode		= spi->mode ? : SPI_MODE_0;
-	spi->max_speed_hz	= spi->max_speed_hz ? : 15000000;
+	spi->max_speed_hz	= spi->max_speed_hz ? : 4 * HZ_PER_MHZ;
 	ret = spi_setup(spi);
 	if (ret)
 		return ret;
-- 
2.39.2