linux-kernel - [PATCH] Input: st1232 - increase "wait ready" timeout

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Message-Id: <20210929152609.2421483-1-john@metanate.com>
Date:   Wed, 29 Sep 2021 16:26:08 +0100
From:   John Keeping <john@...anate.com>
To:     linux-input@...r.kernel.org
Cc:     John Keeping <john@...anate.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] Input: st1232 - increase "wait ready" timeout

I have a ST1633 touch controller which fails to probe due to a timeout
waiting for the controller to become ready.  Increasing the minimum
delay to 100ms ensures that the probe sequence completes successfully.

The ST1633 datasheet says nothing about the maximum delay here and the
ST1232 I2C protocol document says "wait until" with no notion of a
timeout.

Since this only runs once during probe, being generous with the timout
seems reasonable and most likely the device will become ready
eventually.

(It may be worth noting that I saw this issue with a PREEMPT_RT patched
kernel which probably has tighter wakeups from usleep_range() than other
preemption models.)

Fixes: f605be6a57b4 ("Input: st1232 - wait until device is ready before reading resolution")
Signed-off-by: John Keeping <john@...anate.com>
---
 drivers/input/touchscreen/st1232.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/st1232.c b/drivers/input/touchscreen/st1232.c
index 6abae665ca71..9d1dea6996a2 100644
--- a/drivers/input/touchscreen/st1232.c
+++ b/drivers/input/touchscreen/st1232.c
@@ -92,7 +92,7 @@ static int st1232_ts_wait_ready(struct st1232_ts_data *ts)
 	unsigned int retries;
 	int error;
 
-	for (retries = 10; retries; retries--) {
+	for (retries = 100; retries; retries--) {
 		error = st1232_ts_read_data(ts, REG_STATUS, 1);
 		if (!error) {
 			switch (ts->read_buf[0]) {
-- 
2.33.0