Hi Prabhakar,

As discussed separately I would prefer to better understand issue before 
going to this patch.
Nevertheless I have some remarks in code in case we'll need it at the end.

On 9/4/20 10:18 PM, Lad Prabhakar wrote:
> Keep the sensor in software power down mode and wake up only in
> ov5640_set_stream_dvp() callback.
> 
> Signed-off-by: Lad Prabhakar <[email protected]>
> Reviewed-by: Biju Das <[email protected]>
> Tested-by: Jacopo Mondi <[email protected]>
> ---
>   drivers/media/i2c/ov5640.c | 19 ++++++++++++++++---
>   1 file changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index 2fe4a7ac0592..880fde73a030 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -34,6 +34,8 @@
>   #define OV5640_REG_SYS_RESET02              0x3002
>   #define OV5640_REG_SYS_CLOCK_ENABLE02       0x3006
>   #define OV5640_REG_SYS_CTRL0                0x3008
> +#define OV5640_REG_SYS_CTRL0_SW_PWDN 0x42
> +#define OV5640_REG_SYS_CTRL0_SW_PWUP 0x02

For the time being this section was only referring to registers 
addresses and bit details was explained into a comment right before 
affectation, see OV5640_REG_IO_MIPI_CTRL00 for example.

>   #define OV5640_REG_CHIP_ID          0x300a
>   #define OV5640_REG_IO_MIPI_CTRL00   0x300e
>   #define OV5640_REG_PAD_OUTPUT_ENABLE01      0x3017
> @@ -1120,6 +1122,12 @@ static int ov5640_load_regs(struct ov5640_dev *sensor,
>               val = regs->val;
>               mask = regs->mask;
>   
> +             /* remain in power down mode for DVP */
> +             if (regs->reg_addr == OV5640_REG_SYS_CTRL0 &&
> +                 val == OV5640_REG_SYS_CTRL0_SW_PWUP &&
> +                 sensor->ep.bus_type != V4L2_MBUS_CSI2_DPHY)
> +                     continue;
> +

I understand that more or less register OV5640_REG_SYS_CTRL0 (0x3008) 
has been partially removed from big init sequence: for power-up part, 
but power-dwn remains at very beginning of sequence.
We should completely remove 0x3008 from init sequence, including 
power-dwn, and introduce a new function ov5640_sw_powerdown(on/off) that 
should be called at the right place instead.


>               if (mask)
>                       ret = ov5640_mod_reg(sensor, reg_addr, mask, val);
>               else
> @@ -1297,9 +1305,14 @@ static int ov5640_set_stream_dvp(struct ov5640_dev 
> *sensor, bool on)
>        * PAD OUTPUT ENABLE 02
>        * - [7:2]:     D[5:0] output enable
>        */
> -     return ov5640_write_reg(sensor,
> -                             OV5640_REG_PAD_OUTPUT_ENABLE02,
> -                             on ? 0xfc : 0);
> +     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);
>   }
>   
>   static int ov5640_set_stream_mipi(struct ov5640_dev *sensor, bool on)
> 


BR,
Hugues.

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