Re: [PATCH 68/75] media: imx: imx7_mipi_csis: Calculate Ths_settle from source pixel rate

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

On Thu, Jan 07, 2021 at 12:59:24AM +0200, Sakari Ailus wrote:
> On Tue, Jan 05, 2021 at 05:28:45PM +0200, Laurent Pinchart wrote:
> > The Ths_settle timing parameter depends solely on the pixel rate of the
> > source. Calculate it at runtime instead of requiring it to be specified
> > in the device tree.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > ---
> >  drivers/staging/media/imx/imx7-mipi-csis.c | 65 ++++++++++++++++++----
> >  1 file changed, 53 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/staging/media/imx/imx7-mipi-csis.c b/drivers/staging/media/imx/imx7-mipi-csis.c
> > index 3c68ee8b2a59..c83450ac37fa 100644
> > --- a/drivers/staging/media/imx/imx7-mipi-csis.c
> > +++ b/drivers/staging/media/imx/imx7-mipi-csis.c
> > @@ -24,6 +24,7 @@
> >  #include <linux/reset.h>
> >  #include <linux/spinlock.h>
> >  
> > +#include <media/v4l2-ctrls.h>
> >  #include <media/v4l2-device.h>
> >  #include <media/v4l2-fwnode.h>
> >  #include <media/v4l2-mc.h>
> > @@ -233,7 +234,11 @@ struct csi_state {
> >  	struct media_pad pads[CSIS_PADS_NUM];
> >  	struct v4l2_subdev mipi_sd;
> >  	struct v4l2_async_notifier notifier;
> > -	struct v4l2_subdev *src_sd;
> > +
> > +	struct {
> > +		struct v4l2_subdev *sd;
> > +		struct v4l2_ctrl *pixel_rate;
> > +	} src;
> >  
> >  	u8 index;
> >  	struct platform_device *pdev;
> > @@ -482,6 +487,31 @@ static void __mipi_csis_set_format(struct csi_state *state)
> >  	mipi_csis_write(state, MIPI_CSIS_ISPRESOL_CH0, val);
> >  }
> >  
> > +static int mipi_csis_calculate_params(struct csi_state *state)
> > +{
> > +	u64 pixel_rate;
> > +	u32 lane_rate;
> > +
> > +	/* Calculate the line rate from the pixel rate. */
> > +	pixel_rate = v4l2_ctrl_g_ctrl_int64(state->src.pixel_rate);
> 
> Could you instead use v4l2_get_link_freq()?
> 
> I guess we're also moving to the LINK_FREQ control to tell this.

I've developed this patch before we discussed moving to LINQ_FREQ :-)
I'll fix this in v2.

> > +	lane_rate = div_u64(pixel_rate, state->bus.num_data_lanes)
> > +		  * state->csis_fmt->width;
> > +	if (lane_rate < 80000000 || lane_rate > 1500000000) {
> > +		dev_dbg(state->dev, "Out-of-bound lane rate %u\n", lane_rate);
> > +		return -EINVAL;
> > +	}
> > +
> > +	/*
> > +	 * The HSSETTLE counter value is document in a table, but can also
> > +	 * easily be calculated.
> > +	 */
> > +	state->hs_settle = (lane_rate - 5000000) / 45000000;
> 
> Much better, thank you!

-- 
Regards,

Laurent Pinchart