From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> On gen2 the scanline counter behaves a bit differently from the later generations. Instead of adding one to the raw scanline counter value, we must subtract one. v2: Remove the gen3 FIXME. Gen3 behaves like gen4 Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/i915_irq.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c index fc49fb6..40adce0 100644 --- a/drivers/gpu/drm/i915/i915_irq.c +++ b/drivers/gpu/drm/i915/i915_irq.c @@ -724,26 +724,34 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc) struct drm_i915_private *dev_priv = dev->dev_private; const struct drm_display_mode *mode = &crtc->config.adjusted_mode; enum pipe pipe = crtc->pipe; - int vtotal = mode->crtc_vtotal; - int position; + int position, vtotal; + vtotal = mode->crtc_vtotal; if (mode->flags & DRM_MODE_FLAG_INTERLACE) vtotal /= 2; + /* + * The scanline counter increments at the leading edge of hsync. + * + * On most platforms it starts counting from vtotal-1 on the + * first active line. That means the scanline counter value is + * always one less than what we would expect. Ie. just after + * start of vblank, which also occurs at start of hsync (on the + * last active line), the scanline counter will read vblank_start-1. + * + * Gen2 is the exception as the scanline counter starts counting + * from 1 instead of vtotal-1, so we have to subtract one (or + * rather add vtotal-1 to keep the value positive), instead of + * adding one. + */ if (IS_GEN2(dev)) - position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) & DSL_LINEMASK_GEN2; + position = (__raw_i915_read32(dev_priv, PIPEDSL(pipe)) & + DSL_LINEMASK_GEN2) + vtotal - 1; else - position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) & DSL_LINEMASK_GEN3; + position = (__raw_i915_read32(dev_priv, PIPEDSL(pipe)) & + DSL_LINEMASK_GEN3) + 1; - /* - * Scanline counter increments at leading edge of hsync, and - * it starts counting from vtotal-1 on the first active line. - * That means the scanline counter value is always one less - * than what we would expect. Ie. just after start of vblank, - * which also occurs at start of hsync (on the last active line), - * the scanline counter will read vblank_start-1. - */ - return (position + 1) % vtotal; + return position % vtotal; } static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe, -- 1.8.3.2 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
