Attachment 95234 Details for Bug 75725 – [PATCH] drm/i915: Add a workaround for HSW scanline counter weirdness

[patch] [PATCH] drm/i915: Add a workaround for HSW scanline counter weirdness

0001-drm-i915-Add-a-workaround-for-HSW-scanline-counter-w.patch (text/plain), 2.97 KB, created by Ville Syrjala on 2014-03-06 19:20:09 UTC

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Creator: Ville Syrjala

Created: 2014-03-06 19:20:09 UTC

Size: 2.97 KB

patch

obsolete

>From e9ab3b553d49201003b38c8cc162bd1edc6854c7 Mon Sep 17 00:00:00 2001
>From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
>Date: Thu, 6 Mar 2014 20:36:02 +0200
>Subject: [PATCH] drm/i915: Add a workaround for HSW scanline counter weirdness
>MIME-Version: 1.0
>Content-Type: text/plain; charset=UTF-8
>Content-Transfer-Encoding: 8bit
>
>On HSW the scanline counter seems to behave differently depending on
>the output type. eDP on port A does what you would expect an the normal
>+1 fixup is sufficient to cover it. But on HDMI outputs we seem to need
>a +2 fixup. Just assume we always need the +2 fixup and accept the
>slight inaccuracy on eDP.
>
>This fixes a regression introduced in:
> commit 8072bfa6045a264d3913102a35fab125b06603a2
> Author: Ville SyrjÃ¤lÃ¤ <ville.syrjala@linux.intel.com>
> Date:   Mon Oct 28 21:22:52 2013 +0200
>
>    drm/radeon: Move the early vblank IRQ fixup to radeon_get_crtc_scanoutpos()
>
>That commit removed the heuristic that tried to fix up the timestamps
>for vblank interrupts that fire a bit too early. Since then the vblank
>timestamp code would treat some vblank interrupts as spurious since the
>scanline counter would indicate that vblank_start wasn't reached yet.
>That in turn lead to incorrect vblank event sequence numbers being
>reported to userspace, which lead to unsteady framerate in applications
>such as XBMC which uses them for timing purposes.
>
>Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=75725
>Signed-off-by: Ville SyrjÃ¤lÃ¤ <ville.syrjala@linux.intel.com>
>---
> drivers/gpu/drm/i915/i915_irq.c | 22 +++++++++++++++++++++-
> 1 file changed, 21 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
>index 9fec711..72fce3d 100644
>--- a/drivers/gpu/drm/i915/i915_irq.c
>+++ b/drivers/gpu/drm/i915/i915_irq.c
>@@ -702,7 +702,27 @@ static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
> 		else
> 			position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) & DSL_LINEMASK_GEN3;
> 
>-		if (HAS_PCH_SPLIT(dev)) {
>+		if (HAS_DDI(dev)) {
>+			/*
>+			 * On HSW HDMI outputs there seems to be a 2 line
>+			 * difference, whereas eDP has the normal 1 line
>+			 * difference that earlier platforms have. External
>+			 * DP is unknown. For now just check for the 2 line
>+			 * difference case on all output types on HSW+.
>+			 *
>+			 * This might misinterpret the scanline counter being
>+			 * one line too far along on eDP, but that's less
>+			 * dangerous than the alternative since that would lead
>+			 * the vblank timestamp code astray when it sees a
>+			 * scanline count before vblank_start during a vblank
>+			 * interrupt.
>+			 */
>+			if ((in_vbl && (position == vbl_start - 2 ||
>+					position == vbl_start - 1)) ||
>+			    (!in_vbl && (position == vbl_end - 2 ||
>+					 position == vbl_end - 1)))
>+				position = (position + 2) % vtotal;
>+		} else if (HAS_PCH_SPLIT(dev)) {
> 			/*
> 			 * The scanline counter increments at the leading edge
> 			 * of hsync, ie. it completely misses the active portion
>-- 
>1.8.3.2
>

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Attachments on bug 75725: 95055 | 95056 | 95057 | 95058 | 95108 | 95234

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