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Commit 0dae35a3 authored by Ville Syrjälä's avatar Ville Syrjälä
Browse files

drm: Simplify the math in drm_calc_timestamping_constants() 



drm_calc_timestamping_constants() makes the math more complex
than necessary.
- multipying the dotclock by 1000 is pointless, just makes all the
  numbers bigger
- div64_u64() is also pointless, div_u64 is enough
- pixeldur_ns doesn't need any 64bit math

Reviewed-by: default avatar <mario.kleiner.de@gmail.com>
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
parent 21b21560

drivers/gpu/drm/drm_irq.c

+11 −15
Original line number Original line Diff line number Diff line
@@ -451,10 +451,7 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, 
				     const struct drm_display_mode *mode)

				     const struct drm_display_mode *mode)

{

{

	s64 linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;

	s64 linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0;

	u64 dotclock;

	int dotclock = mode->clock;



	/* Dot clock in Hz: */

	dotclock = (u64) mode->clock * 1000;





	/* Fields of interlaced scanout modes are only half a frame duration.

	/* Fields of interlaced scanout modes are only half a frame duration.

	 * Double the dotclock to get half the frame-/line-/pixelduration.

	 * Double the dotclock to get half the frame-/line-/pixelduration.
@@ -464,17 +461,16 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, 




	/* Valid dotclock? */

	/* Valid dotclock? */

	if (dotclock > 0) {

	if (dotclock > 0) {

		int frame_size;

		int frame_size = mode->crtc_htotal * mode->crtc_vtotal;

		/* Convert scanline length in pixels and video dot clock to



		 * line duration, frame duration and pixel duration in

		/*

		 * nanoseconds:

		 * Convert scanline length in pixels and video

		 * dot clock to line duration, frame duration

		 * and pixel duration in nanoseconds:

		 */

		 */

		pixeldur_ns = (s64) div64_u64(1000000000, dotclock);

		pixeldur_ns = 1000000 / dotclock;

		linedur_ns  = (s64) div64_u64(((u64) mode->crtc_htotal *

		linedur_ns  = div_u64((u64) mode->crtc_htotal * 1000000, dotclock);

					      1000000000), dotclock);

		framedur_ns = div_u64((u64) frame_size * 1000000, dotclock);

		frame_size = mode->crtc_htotal * mode->crtc_vtotal;

		framedur_ns = (s64) div64_u64((u64) frame_size * 1000000000,

					      dotclock);

	} else

	} else

		DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",

		DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n",

			  crtc->base.id);

			  crtc->base.id);
@@ -487,7 +483,7 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, 
		  crtc->base.id, mode->crtc_htotal,

		  crtc->base.id, mode->crtc_htotal,

		  mode->crtc_vtotal, mode->crtc_vdisplay);

		  mode->crtc_vtotal, mode->crtc_vdisplay);

	DRM_DEBUG("crtc %d: clock %d kHz framedur %d linedur %d, pixeldur %d\n",

	DRM_DEBUG("crtc %d: clock %d kHz framedur %d linedur %d, pixeldur %d\n",

		  crtc->base.id, (int) dotclock/1000, (int) framedur_ns,

		  crtc->base.id, dotclock, (int) framedur_ns,

		  (int) linedur_ns, (int) pixeldur_ns);

		  (int) linedur_ns, (int) pixeldur_ns);

}

}

EXPORT_SYMBOL(drm_calc_timestamping_constants);

EXPORT_SYMBOL(drm_calc_timestamping_constants);