linux-kernel - [PATCH v5 08/15] media: i2c: rdacm21: Add delay after OV490 reset

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Date:   Wed, 16 Jun 2021 14:46:09 +0200
From:   Jacopo Mondi <jacopo+renesas@...ndi.org>
To:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        kieran.bingham+renesas@...asonboard.com,
        laurent.pinchart+renesas@...asonboard.com,
        niklas.soderlund+renesas@...natech.se, geert@...ux-m68k.org
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: [PATCH v5 08/15] media: i2c: rdacm21: Add delay after OV490 reset

Add a delay after the OV490 chip is put in reset state. The reset
signal shall be held low for at least 250 useconds.

Signed-off-by: Jacopo Mondi <jacopo+renesas@...ndi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
---
 drivers/media/i2c/rdacm21.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
index 553e3f03752b..6be8ce130e78 100644
--- a/drivers/media/i2c/rdacm21.c
+++ b/drivers/media/i2c/rdacm21.c
@@ -469,7 +469,10 @@ static int rdacm21_initialize(struct rdacm21_device *dev)
 	if (ret)
 		return ret;
 
-	/* Enable GPIO1 and hold OV490 in reset during max9271 configuration. */
+	/*
+	 * Enable GPIO1 and hold OV490 in reset during max9271 configuration.
+	 * The reset signal has to be asserted for at least 250 useconds.
+	 */
 	ret = max9271_enable_gpios(&dev->serializer, MAX9271_GPIO1OUT);
 	if (ret)
 		return ret;
@@ -477,6 +480,7 @@ static int rdacm21_initialize(struct rdacm21_device *dev)
 	ret = max9271_clear_gpios(&dev->serializer, MAX9271_GPIO1OUT);
 	if (ret)
 		return ret;
+	usleep_range(250, 500);
 
 	ret = max9271_configure_gmsl_link(&dev->serializer);
 	if (ret)
-- 
2.31.1