linux-kernel - [PATCH v2 08/22] media: i2c: ds90ub953: Speed-up I2C watchdog timer

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Message-Id: <20250124-ub9xx-improvements-v2-8-f7075c99ea20@ideasonboard.com>
Date: Fri, 24 Jan 2025 17:17:45 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Devarsh Thakkar <devarsht@...com>, Jai Luthra <jai.luthra@...asonboard.com>, 
 Sakari Ailus <sakari.ailus@...ux.intel.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Subject: [PATCH v2 08/22] media: i2c: ds90ub953: Speed-up I2C watchdog
 timer

From: Jai Luthra <jai.luthra@...asonboard.com>

On the I2C bus for remote clients (sensors), by default the watchdog
timer expires in 1s. To allow for a quicker system bring-up time, TI
recommends to speed it up to 50us [1].

[1]: Section 7.3.1.1 - https://www.ti.com/lit/gpn/ds90ub953-q1

Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
---
 drivers/media/i2c/ds90ub953.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/media/i2c/ds90ub953.c b/drivers/media/i2c/ds90ub953.c
index 99a4852b9381..4832128dc9c4 100644
--- a/drivers/media/i2c/ds90ub953.c
+++ b/drivers/media/i2c/ds90ub953.c
@@ -54,6 +54,10 @@
 #define UB953_REG_CLKOUT_CTRL0			0x06
 #define UB953_REG_CLKOUT_CTRL1			0x07
 
+#define UB953_REG_I2C_CONTROL2			0x0a
+#define UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT	4
+#define UB953_REG_I2C_CONTROL2_BUS_SPEEDUP	BIT(1)
+
 #define UB953_REG_SCL_HIGH_TIME			0x0b
 #define UB953_REG_SCL_LOW_TIME			0x0c
 
@@ -1320,6 +1324,13 @@ static int ub953_hw_init(struct ub953_data *priv)
 	if (ret)
 		return ret;
 
+	ret = ub953_write(priv, UB953_REG_I2C_CONTROL2,
+			  (1 << UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT) |
+			   UB953_REG_I2C_CONTROL2_BUS_SPEEDUP,
+			  NULL);
+	if (ret)
+		return ret;
+
 	return 0;
 }
 

-- 
2.43.0