Re: [PATCH v4 3/6] media: i2c: ov5640: Enable data pins on poweron for DVP mode

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

Hi Prabhakar,

Thanks for your patches, good to see one more OV5640 stakeholder 
upstreaming some fixes/features.

I'm also using a parallel setup with OV5640 connected on STM32 DCMI 
camera interface.
First basic tests have not shown any regressions on my side but I would 
like to better understand the problem you encountered and the way you 
solve it, see below my comments.


On 9/4/20 10:18 PM, Lad Prabhakar wrote:
> During testing this sensor on iW-RainboW-G21D-Qseven platform in 8-bit DVP
> mode with rcar-vin bridge noticed the capture worked fine for the first run
> (with yavta), but for subsequent runs the bridge driver waited for the
> frame to be captured. Debugging further noticed the data lines were
> enabled/disabled in stream on/off callback and dumping the register
> contents 0x3017/0x3018 in ov5640_set_stream_dvp() reported the correct
> values, but yet frame capturing failed.

Could you show the sequence of V4L2 calls which lead to freeze ?

Reading the patch you proposed, my guess is that issue is coming when 
multiple S_STREAM(on)/S_STREAM(off) are made while power remains, is 
that true ?
I have added some traces in code and tried to reproduce with yavta, 
v4l2-ctl and GStreamer but I'm not able to generate such sequence, here 
is what I got everytime:

[  809.113790] ov5640 0-003c: ov5640_s_power>
[  809.116431] ov5640 0-003c: ov5640_set_power>
[  809.120788] ov5640 0-003c: ov5640_set_power_on>
[  809.622047] ov5640 0-003c: ov5640_set_power_dvp>
[  809.862734] ov5640 0-003c: ov5640_s_stream>
[  809.865462] ov5640 0-003c: ov5640_set_stream_dvp on>
<capturing here>
[  828.549531] ov5640 0-003c: ov5640_s_stream>
[  828.552265] ov5640 0-003c: ov5640_set_stream_dvp off>
[  828.580970] ov5640 0-003c: ov5640_s_power>
[  828.583613] ov5640 0-003c: ov5640_set_power>
[  828.587921] ov5640 0-003c: ov5640_set_power_dvp>
[  828.620346] ov5640 0-003c: ov5640_set_power_off>

Which application/command line are you using to reproduce your problem ?


> 
> To get around this issue data lines are enabled in s_power callback.
> (Also the sensor remains in power down mode if not streaming so power
> consumption shouldn't be affected)

For the time being, I really don't understand why this patch is fixing 
capture freeze.

> 
> Fixes: f22996db44e2d ("media: ov5640: add support of DVP parallel interface")
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
> Tested-by: Jacopo Mondi <jacopo@jmondi.org>
> ---
>   drivers/media/i2c/ov5640.c | 73 +++++++++++++++++++++-----------------
>   1 file changed, 40 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index 8af11d532699..8288728d8704 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -276,8 +276,7 @@ static inline struct v4l2_subdev *ctrl_to_sd(struct v4l2_ctrl *ctrl)
>   /* YUV422 UYVY VGA@30fps */
>   static const struct reg_value ov5640_init_setting_30fps_VGA[] = {
>   	{0x3103, 0x11, 0, 0}, {0x3008, 0x82, 0, 5}, {0x3008, 0x42, 0, 0},
> -	{0x3103, 0x03, 0, 0}, {0x3017, 0x00, 0, 0}, {0x3018, 0x00, 0, 0},
> -	{0x3630, 0x36, 0, 0},
> +	{0x3103, 0x03, 0, 0}, {0x3630, 0x36, 0, 0},
>   	{0x3631, 0x0e, 0, 0}, {0x3632, 0xe2, 0, 0}, {0x3633, 0x12, 0, 0},
>   	{0x3621, 0xe0, 0, 0}, {0x3704, 0xa0, 0, 0}, {0x3703, 0x5a, 0, 0},
>   	{0x3715, 0x78, 0, 0}, {0x3717, 0x01, 0, 0}, {0x370b, 0x60, 0, 0},
> @@ -1283,33 +1282,6 @@ static int ov5640_set_stream_dvp(struct ov5640_dev *sensor, bool on)
>   	if (ret)
>   		return ret;
>   
> -	/*
> -	 * enable VSYNC/HREF/PCLK DVP control lines
> -	 * & D[9:6] DVP data lines
> -	 *
> -	 * PAD OUTPUT ENABLE 01
> -	 * - 6:		VSYNC output enable
> -	 * - 5:		HREF output enable
> -	 * - 4:		PCLK output enable
> -	 * - [3:0]:	D[9:6] output enable
> -	 */
> -	ret = ov5640_write_reg(sensor,
> -			       OV5640_REG_PAD_OUTPUT_ENABLE01,
> -			       on ? 0x7f : 0);
> -	if (ret)
> -		return ret;
> -
> -	/*
> -	 * enable D[5:0] DVP data lines
> -	 *
> -	 * PAD OUTPUT ENABLE 02
> -	 * - [7:2]:	D[5:0] output enable
> -	 */
> -	ret = ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE02,
> -			       on ? 0xfc : 0);
> -	if (ret)
> -		return ret;
> -
>   	return ov5640_write_reg(sensor, OV5640_REG_SYS_CTRL0, on ?
>   				OV5640_REG_SYS_CTRL0_SW_PWUP :
>   				OV5640_REG_SYS_CTRL0_SW_PWDN);
> @@ -2069,6 +2041,40 @@ static int ov5640_set_power_mipi(struct ov5640_dev *sensor, bool on)
>   	return 0;
>   }
>   
> +static int ov5640_set_power_dvp(struct ov5640_dev *sensor, bool on)
> +{
> +	int ret;
> +
> +	if (!on) {
> +		/* Reset settings to their default values. */
> +		ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE01, 0x00);
> +		ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE02, 0x00);
> +		return 0;
> +	}
> +
> +	/*
> +	 * enable VSYNC/HREF/PCLK DVP control lines
> +	 * & D[9:6] DVP data lines
> +	 *
> +	 * PAD OUTPUT ENABLE 01
> +	 * - 6:		VSYNC output enable
> +	 * - 5:		HREF output enable
> +	 * - 4:		PCLK output enable
> +	 * - [3:0]:	D[9:6] output enable
> +	 */
> +	ret = ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE01, 0x7f);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * enable D[5:0] DVP data lines
> +	 *
> +	 * PAD OUTPUT ENABLE 02
> +	 * - [7:2]:	D[5:0] output enable
> +	 */
> +	return ov5640_write_reg(sensor, OV5640_REG_PAD_OUTPUT_ENABLE02, 0xfc);
> +}
> +
>   static int ov5640_set_power(struct ov5640_dev *sensor, bool on)
>   {
>   	int ret = 0;
> @@ -2083,11 +2089,12 @@ static int ov5640_set_power(struct ov5640_dev *sensor, bool on)
>   			goto power_off;
>   	}
>   
> -	if (sensor->ep.bus_type == V4L2_MBUS_CSI2_DPHY) {
> +	if (sensor->ep.bus_type == V4L2_MBUS_CSI2_DPHY)
>   		ret = ov5640_set_power_mipi(sensor, on);
> -		if (ret)
> -			goto power_off;
> -	}
> +	else
> +		ret = ov5640_set_power_dvp(sensor, on);
> +	if (ret)
> +		goto power_off;
>   
>   	if (!on)
>   		ov5640_set_power_off(sensor);
> 

Best regards,
Hugues.