From 0dae35a3886c883bf993c8776dafd8a3bb2fef44 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Ville=20Syrj=C3=A4l=C3=A4?= Date: Sat, 26 Oct 2013 17:11:01 +0300 Subject: [PATCH] drm: Simplify the math in drm_calc_timestamping_constants() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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: mario.kleiner.de@gmail.com Signed-off-by: Ville Syrjälä --- drivers/gpu/drm/drm_irq.c | 26 +++++++++++--------------- 1 file changed, 11 insertions(+), 15 deletions(-) diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 03f6a14..3283669 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -451,10 +451,7 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, const struct drm_display_mode *mode) { s64 linedur_ns = 0, pixeldur_ns = 0, framedur_ns = 0; - u64 dotclock; - - /* Dot clock in Hz: */ - dotclock = (u64) mode->clock * 1000; + int dotclock = mode->clock; /* Fields of interlaced scanout modes are only half a frame duration. * 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? */ if (dotclock > 0) { - int frame_size; - /* Convert scanline length in pixels and video dot clock to - * line duration, frame duration and pixel duration in - * nanoseconds: + 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: */ - pixeldur_ns = (s64) div64_u64(1000000000, dotclock); - linedur_ns = (s64) div64_u64(((u64) mode->crtc_htotal * - 1000000000), dotclock); - frame_size = mode->crtc_htotal * mode->crtc_vtotal; - framedur_ns = (s64) div64_u64((u64) frame_size * 1000000000, - dotclock); + pixeldur_ns = 1000000 / dotclock; + linedur_ns = div_u64((u64) mode->crtc_htotal * 1000000, dotclock); + framedur_ns = div_u64((u64) frame_size * 1000000, dotclock); } else DRM_ERROR("crtc %d: Can't calculate constants, dotclock = 0!\n", crtc->base.id); @@ -487,7 +483,7 @@ void drm_calc_timestamping_constants(struct drm_crtc *crtc, crtc->base.id, mode->crtc_htotal, mode->crtc_vtotal, mode->crtc_vdisplay); 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); } EXPORT_SYMBOL(drm_calc_timestamping_constants); -- 2.7.4