linux-kernel - [PATCH] media: dw9714: Fix powerup sequence

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Message-Id: <20251210-dw9174-timing-v1-1-4a5036465727@chromium.org>
Date: Wed, 10 Dec 2025 07:53:43 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, Ondrej Jirman <megi@....cz>, 
 Hans Verkuil <hverkuil@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH] media: dw9714: Fix powerup sequence

We have experienced seen multiple I2C errors while doing stress test on
the module:

dw9714 i2c-PRP0001:01: dw9714_vcm_resume I2C failure: -5
dw9714 i2c-PRP0001:01: I2C write fail

Inspecting the powerup sequence we found that it does not match the
documentation at:
https://blog.arducam.com/downloads/DW9714A-DONGWOON(Autofocus_motor_manual).pdf

"""
(2) DW9714A requires waiting time of 12ms after power on. During this
waiting time, the offset calibration of internal amplifier is
operating for minimization of output offset current .
"""

This patch increases the powerup delay to follow the documentation.

Fixes: 9d00ccabfbb5 ("media: i2c: dw9714: Fix occasional probe errors")
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/i2c/dw9714.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/dw9714.c b/drivers/media/i2c/dw9714.c
index 1e7ad355a388cfc37253bd764ec8df98f59beeea..3288de539452ebae41daa0988b2d52f27a790da7 100644
--- a/drivers/media/i2c/dw9714.c
+++ b/drivers/media/i2c/dw9714.c
@@ -149,7 +149,7 @@ static int dw9714_power_up(struct dw9714_device *dw9714_dev)
 
 	gpiod_set_value_cansleep(dw9714_dev->powerdown_gpio, 0);
 
-	usleep_range(1000, 2000);
+	usleep_range(12000, 14000);
 
 	return 0;
 }

---
base-commit: f7231cff1f3ff8259bef02dc4999bc132abf29cf
change-id: 20251210-dw9174-timing-9e58903399c9

Best regards,
-- 
Ricardo Ribalda <ribalda@...omium.org>