Hi Sakari,

-----Original Message-----
From: Sakari Ailus [mailto:sakari.ailus@iki.fi]
Sent: 2017年12月14日 4:06
To: Wenyou Yang - A41535 <redacted>; Mauro Carvalho
Chehab [off-list ref]; Rob Herring [off-list ref];
Mark Rutland [off-list ref]
Cc: linux-kernel@vger.kernel.org; Nicolas Ferre - M43238
[off-list ref]; devicetree@vger.kernel.org; Jonathan Corbet
[off-list ref]; Hans Verkuil [off-list ref]; linux-arm-
kernel@lists.infradead.org; Linux Media Mailing List <linux-
media@vger.kernel.org>; Songjun Wu [off-list ref]
Subject: Re: [PATCH v9 2/2] media: i2c: Add the ov7740 image sensor driver

Hi Wenyou,

Wenyou Yang wrote:
...

quoted

+static int ov7740_start_streaming(struct ov7740 *ov7740) {
+	int ret;
+
+	if (ov7740->fmt) {
+		ret = regmap_multi_reg_write(ov7740->regmap,
+					     ov7740->fmt->regs,
+					     ov7740->fmt->reg_num);
+		if (ret)
+			return ret;
+	}
+
+	if (ov7740->frmsize) {
+		ret = regmap_multi_reg_write(ov7740->regmap,
+					     ov7740->frmsize->regs,
+					     ov7740->frmsize->reg_num);
+		if (ret)
+			return ret;
+	}
+
+	return __v4l2_ctrl_handler_setup(ov7740->subdev.ctrl_handler);

I believe you're still setting the controls after starting streaming.

Yes, it sees it does so.

The OV7740 sensor generates the stream pixel data at the constant frame rate, no such start or stop control. 

--
Sakari Ailus
sakari.ailus@iki.fi

Wenyou Yang