Re: [PATCH v2 3/4] media: i2c: ov5640: Add support for BT656 mode

[Hugues FRUCHET <hugues.fruchet@st.com>]

Hi Prabhakar,

I'm currently testing the OV5640 CCIR656 embedded synchronisation mode 
on STM32MP1 running STM32 DCMI camera interface.
Tests not yet fully completed but sounds good, more details below.

On 8/3/20 4:31 PM, Lad Prabhakar wrote:
> Enable support for BT656 mode.
> 
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
>   drivers/media/i2c/ov5640.c | 40 +++++++++++++++++++++++++++-----------
>   1 file changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index ec444bee2ce9..08c67250042f 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -82,6 +82,7 @@
>   #define OV5640_REG_VFIFO_HSIZE		0x4602
>   #define OV5640_REG_VFIFO_VSIZE		0x4604
>   #define OV5640_REG_JPG_MODE_SELECT	0x4713
> +#define OV5640_REG_CCIR656_CTRL00	0x4730
>   #define OV5640_REG_POLARITY_CTRL00	0x4740
>   #define OV5640_REG_MIPI_CTRL00		0x4800
>   #define OV5640_REG_DEBUG_MODE		0x4814
> @@ -1216,6 +1217,18 @@ static int ov5640_set_autogain(struct ov5640_dev *sensor, bool on)
>   			      BIT(1), on ? 0 : BIT(1));
>   }
>   
> +static int ov5640_set_stream_bt656(struct ov5640_dev *sensor, bool on)
> +{
> +	int ret;
> +
> +	ret = ov5640_write_reg(sensor, OV5640_REG_CCIR656_CTRL00, on ? 0x1 : 0x00);
> +	if (ret)
> +		return ret;

Please add a comment explaining bit fields from datasheet:
Bit[7]: SYNC code selection
0: Automatically generate SYNC code
1: SYNC code from register setting 0x4732~4735
Bit[4:3]: Blank toggle data options
00: Toggle data is 1'h040/1'h200
Bit[1]: Clip data disable (so clip is enabled)
Bit[0]: CCIR656 mode enable

So 0x1 stands for CCIR656 with automatic SYNC codes: SAV/EAV with 
default values ie SAV=0xFF000080 & EAV=0xFF00009d.

On STM32 platform, this correspond to DCMI configuration ESCR=0xff9d80ff 
and ESUR=0xffffffff.
On Renesas platform, I have not seen any configuration in code, this 
SAV/EAV mode seems to be handled by default by hardware, do you confirm ?

Note that another CCIR656 embedded synchro mode could be used with 
custom synchro codes FS/FE/LS/LE in registers 0x4732-0x4735, this
mode is enabled with CCIR656_CTRL00(0x4730) set to 0x81:
Bit[7]: SYNC code selection
1: SYNC code from register setting 0x4732~4735

> +
> +	return ov5640_write_reg(sensor, OV5640_REG_SYS_CTRL0, on ?
> +				OV5640_SOFTWARE_WAKEUP : OV5640_SOFTWARE_PWDN);
> +}
> +
>   static int ov5640_set_stream_dvp(struct ov5640_dev *sensor, bool on)
>   {
>   	return ov5640_write_reg(sensor, OV5640_REG_SYS_CTRL0, on ?
> @@ -2022,18 +2035,20 @@ static int ov5640_set_dvp(struct ov5640_dev *sensor, bool on)
>   	 *		datasheet and hardware, 0 is active high
>   	 *		and 1 is active low...)
>   	 */
> -	if (flags & V4L2_MBUS_PCLK_SAMPLE_RISING)
> -		pclk_pol = 1;
> -	if (flags & V4L2_MBUS_HSYNC_ACTIVE_HIGH)
> -		hsync_pol = 1;
> -	if (flags & V4L2_MBUS_VSYNC_ACTIVE_LOW)
> -		vsync_pol = 1;
> +	if (sensor->ep.bus_type == V4L2_MBUS_PARALLEL) {
> +		if (flags & V4L2_MBUS_PCLK_SAMPLE_RISING)
> +			pclk_pol = 1;
> +		if (flags & V4L2_MBUS_HSYNC_ACTIVE_HIGH)
> +			hsync_pol = 1;
> +		if (flags & V4L2_MBUS_VSYNC_ACTIVE_LOW)
> +			vsync_pol = 1;
>   
> -	ret = ov5640_write_reg(sensor, OV5640_REG_POLARITY_CTRL00,
> -			       (pclk_pol << 5) | (hsync_pol << 1) | vsync_pol);
> +		ret = ov5640_write_reg(sensor, OV5640_REG_POLARITY_CTRL00,
> +				       (pclk_pol << 5) | (hsync_pol << 1) | vsync_pol);
>   
> -	if (ret)
> -		return ret;
> +		if (ret)
> +			return ret;
> +	}
>   
>   	/*
>   	 * powerdown MIPI TX/RX PHY & disable MIPI
> @@ -2057,7 +2072,8 @@ static int ov5640_set_dvp(struct ov5640_dev *sensor, bool on)
>   	 * - 4:		PCLK output enable
>   	 * - [3:0]:	D[9:6] output enable
>   	 */
> -	ret = ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE01, 0x7f);
> +	ret = ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE01,
> +			       sensor->ep.bus_type == V4L2_MBUS_PARALLEL ? 0x7f : 0x1f);
>   	if (ret)
>   		return ret;
>   
> @@ -2911,6 +2927,8 @@ static int ov5640_s_stream(struct v4l2_subdev *sd, int enable)
>   
>   		if (sensor->ep.bus_type == V4L2_MBUS_CSI2_DPHY)
>   			ret = ov5640_set_stream_mipi(sensor, enable);
> +		else if (sensor->ep.bus_type == V4L2_MBUS_BT656)
> +			ret = ov5640_set_stream_bt656(sensor, enable);
>   		else
>   			ret = ov5640_set_stream_dvp(sensor, enable);
>   
> 

BR, Hugues.