Re: [PATCH 2/3] media: ov5640: add PIXEL_RATE and LINK_FREQ controls

[Maxime Ripard <maxime.ripard@bootlin.com>]

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Hi,

On Fri, Apr 20, 2018 at 11:44:18AM +0200, Daniel Mack wrote:
> Add v4l2 controls to report the pixel and MIPI link rates of each mode.
> The camss camera subsystem needs them to set up the correct hardware
> clocks.
> 
> Tested on msm8016 based hardware.
> 
> Signed-off-by: Daniel Mack <daniel@zonque.org>
> ---
>  drivers/media/i2c/ov5640.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 77 insertions(+)
> 
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index 96f1564abdf5..78669ed386cd 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -91,6 +91,20 @@
>  #define OV5640_REG_SDE_CTRL5		0x5585
>  #define OV5640_REG_AVG_READOUT		0x56a1
>  
> +#define OV5640_LINK_FREQ_111	0
> +#define OV5640_LINK_FREQ_166	1
> +#define OV5640_LINK_FREQ_222	2
> +#define OV5640_LINK_FREQ_333	3
> +#define OV5640_LINK_FREQ_666	4
> +
> +static const s64 link_freq_menu_items[] = {
> +	111066666,
> +	166600000,
> +	222133333,
> +	332200000,
> +	666400000,
> +};
> +
>  enum ov5640_mode_id {
>  	OV5640_MODE_QCIF_176_144 = 0,
>  	OV5640_MODE_QVGA_320_240,
> @@ -167,12 +181,18 @@ struct ov5640_mode_info {
>  	enum ov5640_downsize_mode dn_mode;
>  	u32 width;
>  	u32 height;
> +	u32 pixel_rate;
> +	u32 link_freq_idx;
>  	const struct reg_value *reg_data;
>  	u32 reg_data_size;
>  };
>  
>  struct ov5640_ctrls {
>  	struct v4l2_ctrl_handler handler;
> +	struct {
> +		struct v4l2_ctrl *link_freq;
> +		struct v4l2_ctrl *pixel_rate;
> +	};
>  	struct {
>  		struct v4l2_ctrl *auto_exp;
>  		struct v4l2_ctrl *exposure;
> @@ -732,6 +752,8 @@ static const struct ov5640_mode_info ov5640_mode_init_data = {
>  	.dn_mode	= SUBSAMPLING,
>  	.width		= 640,
>  	.height		= 480,
> +	.pixel_rate	= 27766666,
> +	.link_freq_idx	= OV5640_LINK_FREQ_111,

I'm not sure where this is coming from, but on a parallel sensor I
have a quite different pixel rate.

I have a serie ongoing that tries to deal with this, hopefully in
order to get rid of all the clock setup done in the initialiasation
array.

See https://patchwork.linuxtv.org/patch/48710/ for the patch and
https://www.spinics.net/lists/linux-media/msg132201.html for a
discussion on what the clock tree might look like on a MIPI-CSI bus.

Feel free to step in the discussion.
Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

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