2017-09-11 01:53:54

by Jacob Chen

Subject: [PATCH] media: i2c: OV5647: ensure clock lane in LP-11 state before streaming on

When I was supporting Rpi Camera Module on the ASUS Tinker board,
I found this driver have some issues with rockchip's mipi-csi driver.
It didn't place clock lane in LP-11 state before performing
D-PHY initialisation.

>From our experience, on some OV sensors,
LP-11 state is not achieved while BIT(5)-0x4800 is cleared.

So let's set BIT(5) and BIT(0) both while not streaming, in order to
coax the clock lane into LP-11 state.

0x4800 : MIPI CTRL 00
BIT(5) : clock lane gate enable
0: continuous
1: none-continuous
BIT(0) : manually set clock lane
0: Not used
1: used

Changes in V2:
modify commit messages

Signed-off-by: Jacob Chen <[email protected]>
---
drivers/media/i2c/ov5647.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
index 95ce90f..247302d 100644
--- a/drivers/media/i2c/ov5647.c
+++ b/drivers/media/i2c/ov5647.c
@@ -253,6 +253,10 @@ static int ov5647_stream_on(struct v4l2_subdev *sd)
{
int ret;

+ ret = ov5647_write(sd, 0x4800, 0x04);
+ if (ret < 0)
+ return ret;
+
ret = ov5647_write(sd, 0x4202, 0x00);
if (ret < 0)
return ret;
@@ -264,6 +268,10 @@ static int ov5647_stream_off(struct v4l2_subdev *sd)
{
int ret;

+ ret = ov5647_write(sd, 0x4800, 0x25);
+ if (ret < 0)
+ return ret;
+
ret = ov5647_write(sd, 0x4202, 0x0f);
if (ret < 0)
return ret;
@@ -320,7 +328,10 @@ static int __sensor_init(struct v4l2_subdev *sd)
return ret;
}

- return ov5647_write(sd, 0x4800, 0x04);
+ /*
+ * stream off to make the clock lane into LP-11 state.
+ */
+ return ov5647_stream_off(sd);
}

static int ov5647_sensor_power(struct v4l2_subdev *sd, int on)
--
2.7.4

2017-09-18 13:08:42

by Sakari Ailus

Subject: Re: [PATCH] media: i2c: OV5647: ensure clock lane in LP-11 state before streaming on

Hi Jacob,

On Mon, Sep 11, 2017 at 09:53:40AM +0800, Jacob Chen wrote:
> When I was supporting Rpi Camera Module on the ASUS Tinker board,
> I found this driver have some issues with rockchip's mipi-csi driver.
> It didn't place clock lane in LP-11 state before performing
> D-PHY initialisation.
>
> From our experience, on some OV sensors,
> LP-11 state is not achieved while BIT(5)-0x4800 is cleared.
>
> So let's set BIT(5) and BIT(0) both while not streaming, in order to
> coax the clock lane into LP-11 state.
>
> 0x4800 : MIPI CTRL 00
> BIT(5) : clock lane gate enable
> 0: continuous
> 1: none-continuous
> BIT(0) : manually set clock lane
> 0: Not used
> 1: used
>
> Changes in V2:
> modify commit messages

Change log doesn't belong to the commit message.

>
> Signed-off-by: Jacob Chen <[email protected]>
> ---
> drivers/media/i2c/ov5647.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
> index 95ce90f..247302d 100644
> --- a/drivers/media/i2c/ov5647.c
> +++ b/drivers/media/i2c/ov5647.c
> @@ -253,6 +253,10 @@ static int ov5647_stream_on(struct v4l2_subdev *sd)
> {
> int ret;
>
> + ret = ov5647_write(sd, 0x4800, 0x04);

Could you use macros for the register bits instead of using magic number,
please, especially now that it appears that the meaning of these bits is
known?

> + if (ret < 0)
> + return ret;
> +
> ret = ov5647_write(sd, 0x4202, 0x00);
> if (ret < 0)
> return ret;
> @@ -264,6 +268,10 @@ static int ov5647_stream_off(struct v4l2_subdev *sd)
> {
> int ret;
>
> + ret = ov5647_write(sd, 0x4800, 0x25);
> + if (ret < 0)
> + return ret;
> +
> ret = ov5647_write(sd, 0x4202, 0x0f);
> if (ret < 0)
> return ret;
> @@ -320,7 +328,10 @@ static int __sensor_init(struct v4l2_subdev *sd)
> return ret;
> }
>
> - return ov5647_write(sd, 0x4800, 0x04);
> + /*
> + * stream off to make the clock lane into LP-11 state.
> + */
> + return ov5647_stream_off(sd);
> }
>
> static int ov5647_sensor_power(struct v4l2_subdev *sd, int on)
> --
> 2.7.4
>

--
Kind regards,

Sakari Ailus
e-mail: [email protected]