[media] media: ov7670: Add possibility to disable pixclk during hblank

Some bridge drivers capture pixels during blanking periods if
pixclk is enabled. In order to avoid capturing bogus data we need to
disable pixclk in the sensor during those blanking periods.

Acked-by: Jonathan Corbet <[e-mail]>
Signed-off-by: Javier Martin <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/i2c/ov7670.c

···
 	u8 clkrc;			/* Clock divider value */
 	bool use_smbus;			/* Use smbus I/O instead of I2C */
 	bool pll_bypass;
+	bool pclk_hb_disable;
 	const struct ov7670_devtype *devtype; /* Device specifics */
 };
 
···
 		 */
 		if (config->pll_bypass && id->driver_data != MODEL_OV7670)
 			info->pll_bypass = true;
+
+		if (config->pclk_hb_disable)
+			info->pclk_hb_disable = true;
 	}
 
 	/* Make sure it's an ov7670 */
···
 	tpf.numerator = 1;
 	tpf.denominator = 30;
 	info->devtype->set_framerate(sd, &tpf);
+
+	if (info->pclk_hb_disable)
+		ov7670_write(sd, REG_COM10, COM10_PCLK_HB);
 
 	return 0;
 }

include/media/ov7670.h

···
 	int clock_speed;		/* External clock speed (MHz) */
 	bool use_smbus;			/* Use smbus I/O instead of I2C */
 	bool pll_bypass;		/* Choose whether to bypass the PLL */
+	bool pclk_hb_disable;		/* Disable toggling pixclk during horizontal blanking */
 };
 
 #endif