[PATCH v5 8/9] serial: sc16is7xx: add post reset delay

From: Hugo Villeneuve
Date: Thu Jun 01 2023 - 12:49:16 EST


From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>

Make sure we wait at least 3us before initiating communication with
the device after reset.

Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
Reviewed-by: Lech Perczak <lech.perczak@xxxxxxxxxxxxxxx>
Tested-by: Lech Perczak <lech.perczak@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/sc16is7xx.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 388c1d490853..9b2d58023c55 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1521,6 +1521,12 @@ static int sc16is7xx_probe(struct device *dev,
regmap_write(s->regmap, SC16IS7XX_IOCONTROL_REG << SC16IS7XX_REG_SHIFT,
SC16IS7XX_IOCONTROL_SRESET_BIT);

+ /*
+ * After reset, the host must wait at least 3us before initializing a
+ * communication with the device.
+ */
+ usleep_range(5, 10);
+
for (i = 0; i < devtype->nr_uart; ++i) {
s->p[i].line = i;
/* Initialize port data */
--
2.30.2