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

From: Hugues FRUCHET
Date: Mon Sep 07 2020 - 05:44:47 EST


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@xxxxxxxxxxxxxx>
> Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> Tested-by: Jacopo Mondi <jacopo@xxxxxxxxxx>
> ---
> 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.