Hi Andrey
On Tue, 26 Jan 2021 at 07:50, Andrey Konovalov
<andrey.konovalov@xxxxxxxxxx> wrote:
>
> This control is needed for imx219 driver, as the link frequency
> is independent from the pixel rate in this case, and can't be
> calculated from the pixel rate.
>
> Signed-off-by: Andrey Konovalov <andrey.konovalov@xxxxxxxxxx>
> ---
> drivers/media/i2c/imx219.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/i2c/imx219.c b/drivers/media/i2c/imx219.c
> index 92a8d52776b8..6e3382b85a90 100644
> --- a/drivers/media/i2c/imx219.c
> +++ b/drivers/media/i2c/imx219.c
> @@ -390,6 +390,10 @@ static const struct imx219_reg raw10_framefmt_regs[] = {
> {0x0309, 0x0a},
> };
>
> +static const s64 imx219_link_freq_menu[] = {
> + IMX219_DEFAULT_LINK_FREQ,
Link frequency is one of the parameters that is largely irrelevant on
the Pi, so I've partially ignored it.
Is the link frequency really the same for all modes? Even 8 bit vs 10
bit readout?
The pixel rate is constant at 182.4Mpix/s for all modes.
Switching to 8 bit changes register 0x0309 (op_pix_clk_div) from 10 to 8.
Figure 43 "Clock System Block Diagram" in the datasheet I have says
this reduces the divider to the FIFO between the pipeline and MIPI. As
we haven't changed PLL2 or Pre-div2 I'd expect the link frequency to
stay the same, but that leaves me confused over that FIFO clock as
it'll go UP in frequency. I can't quite see how that works, but it
clearly does.
Both 8 and 10 bit modes do read out at the same frame / pixel rate,
therefore that bit is correct, but that leaves me puzzling over link
frequency. I have no information on how big that FIFO is, or how it's
clocked on input and output.
Simplest option is that as I need to go into the office in the next
day or so I'll pop into the lab and measure it in each mode.
Otherwise I have no issues with the implementation of the patch.
Dave
> +};
> +
> static const char * const imx219_test_pattern_menu[] = {
> "Disabled",
> "Color Bars",
> @@ -547,6 +551,7 @@ struct imx219 {
> struct v4l2_ctrl_handler ctrl_handler;
> /* V4L2 Controls */
> struct v4l2_ctrl *pixel_rate;
> + struct v4l2_ctrl *link_freq;
> struct v4l2_ctrl *exposure;
> struct v4l2_ctrl *vflip;
> struct v4l2_ctrl *hflip;
> @@ -1269,7 +1274,7 @@ static int imx219_init_controls(struct imx219 *imx219)
> int i, ret;
>
> ctrl_hdlr = &imx219->ctrl_handler;
> - ret = v4l2_ctrl_handler_init(ctrl_hdlr, 11);
> + ret = v4l2_ctrl_handler_init(ctrl_hdlr, 12);
> if (ret)
> return ret;
>
> @@ -1283,6 +1288,14 @@ static int imx219_init_controls(struct imx219 *imx219)
> IMX219_PIXEL_RATE, 1,
> IMX219_PIXEL_RATE);
>
> + imx219->link_freq =
> + v4l2_ctrl_new_int_menu(ctrl_hdlr, &imx219_ctrl_ops,
> + V4L2_CID_LINK_FREQ,
> + ARRAY_SIZE(imx219_link_freq_menu) - 1, 0,
> + imx219_link_freq_menu);
> + if (imx219->link_freq)
> + imx219->link_freq->flags |= V4L2_CTRL_FLAG_READ_ONLY;
> +
> /* Initial vblank/hblank/exposure parameters based on current mode */
> imx219->vblank = v4l2_ctrl_new_std(ctrl_hdlr, &imx219_ctrl_ops,
> V4L2_CID_VBLANK, IMX219_VBLANK_MIN,
> --
> 2.17.1
>
