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Commit 87f9ed85 authored by Jose Abreu's avatar Jose Abreu Committed by Mauro Carvalho Chehab
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media: v4l2-dv-timings: Introduce v4l2_calc_timeperframe helper 



A new helper function was introduced to facilitate the calculation
of time per frame value whenever we have access to the full
v4l2_dv_timings structure.

This should be used only for receivers and only when there is
enough accuracy in the measured pixel clock value as well as in
the horizontal/vertical values.

Signed-off-by: default avatarJose Abreu <joabreu@synopsys.com>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
parent f992cee5

drivers/media/v4l2-core/v4l2-dv-timings.c

+39 −0
Original line number Diff line number Diff line
@@ -373,6 +373,45 @@ struct v4l2_fract v4l2_dv_timings_aspect_ratio(const struct v4l2_dv_timings *t) 
}

EXPORT_SYMBOL_GPL(v4l2_dv_timings_aspect_ratio);



/** v4l2_calc_timeperframe - helper function to calculate timeperframe based

 *	v4l2_dv_timings fields.

 * @t - Timings for the video mode.

 *

 * Calculates the expected timeperframe using the pixel clock value and

 * horizontal/vertical measures. This means that v4l2_dv_timings structure

 * must be correctly and fully filled.

 */

struct v4l2_fract v4l2_calc_timeperframe(const struct v4l2_dv_timings *t)

{

	const struct v4l2_bt_timings *bt = &t->bt;

	struct v4l2_fract fps_fract = { 1, 1 };

	unsigned long n, d;

	u32 htot, vtot, fps;

	u64 pclk;



	if (t->type != V4L2_DV_BT_656_1120)

		return fps_fract;



	htot = V4L2_DV_BT_FRAME_WIDTH(bt);

	vtot = V4L2_DV_BT_FRAME_HEIGHT(bt);

	pclk = bt->pixelclock;



	if ((bt->flags & V4L2_DV_FL_CAN_DETECT_REDUCED_FPS) &&

	    (bt->flags & V4L2_DV_FL_REDUCED_FPS))

		pclk = div_u64(pclk * 1000ULL, 1001);



	fps = (htot * vtot) > 0 ? div_u64((100 * pclk), (htot * vtot)) : 0;

	if (!fps)

		return fps_fract;



	rational_best_approximation(fps, 100, fps, 100, &n, &d);



	fps_fract.numerator = d;

	fps_fract.denominator = n;

	return fps_fract;

}

EXPORT_SYMBOL_GPL(v4l2_calc_timeperframe);



/*

 * CVT defines

 * Based on Coordinated Video Timings Standard

include/media/v4l2-dv-timings.h

+11 −0
Original line number Diff line number Diff line
@@ -10,6 +10,17 @@ 


#include <linux/videodev2.h>



/**

 * v4l2_calc_timeperframe - helper function to calculate timeperframe based

 *	v4l2_dv_timings fields.

 * @t: Timings for the video mode.

 *

 * Calculates the expected timeperframe using the pixel clock value and

 * horizontal/vertical measures. This means that v4l2_dv_timings structure

 * must be correctly and fully filled.

 */

struct v4l2_fract v4l2_calc_timeperframe(const struct v4l2_dv_timings *t);



/*

 * v4l2_dv_timings_presets: list of all dv_timings presets.

 */