[PATCH v2 9/9] drm/i915: Fix gen2 and hsw+ scanline counter

ville.syrjala
2014-05-15T17:32:09Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

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.

On HSW/BDW the scanline counter requires a +2 adjustment on HDMI
outputs. DP outputs on the on the other require the typical +1
adjustment.

As the fixup we must apply to the hardware scanline counter
depends on several factors, compute the desired offset at modeset
time and tuck it away for when it's needed.

v2: Clarify HSW+ situation

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
drivers/gpu/drm/i915/i915_irq.c | 14 ++++-------
drivers/gpu/drm/i915/intel_display.c | 45 +++++++++++++++++++++++++++++++++++-
drivers/gpu/drm/i915/intel_drv.h | 2 ++
3 files changed, 51 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index bb9b061..80003b5 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -818,9 +818,9 @@ 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;

@@ -830,14 +830,10 @@ static int __intel_get_crtc_scanline(struct intel_crtc *crtc)
position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)) & DSL_LINEMASK_GEN3;

/*
- * 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.
+ * See update_scanline_offset() for the details on the
+ * scanline_offset adjustment.
*/
- return (position + 1) % vtotal;
+ return (position + crtc->scanline_offset) % vtotal;
}

static int i915_get_crtc_scanoutpos(struct drm_device *dev, int pipe,
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0f8f9bc..f7222d7 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10164,6 +10164,44 @@ void ironlake_check_encoder_dotclock(const struct intel_crtc_config *pipe_config
pipe_config->adjusted_mode.crtc_clock, dotclock);
}

+static void update_scanline_offset(struct intel_crtc *crtc)
+{
+ struct drm_device *dev = crtc->base.dev;
+
+ /*
+ * 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.
+ *
+ * On gen2 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.
+ *
+ * On HSW+ the behaviour of the scanline counter depends on the output
+ * type. For DP ports it behaves like most other platforms, but on HDMI
+ * there's an extra 1 line difference. So we need to add two instead of
+ * one to the value.
+ */
+ if (IS_GEN2(dev)) {
+ const struct drm_display_mode *mode = &crtc->config.adjusted_mode;
+ int vtotal;
+
+ vtotal = mode->crtc_vtotal;
+ if (mode->flags & DRM_MODE_FLAG_INTERLACE)
+ vtotal /= 2;
+
+ crtc->scanline_offset = vtotal - 1;
+ } else if (HAS_DDI(dev) &&
+ intel_pipe_has_type(&crtc->base, INTEL_OUTPUT_HDMI)) {
+ crtc->scanline_offset = 2;
+ } else
+ crtc->scanline_offset = 1;
+}
+
static int __intel_set_mode(struct drm_crtc *crtc,
struct drm_display_mode *mode,
int x, int y, struct drm_framebuffer *fb)
@@ -10262,8 +10300,11 @@ static int __intel_set_mode(struct drm_crtc *crtc,
}

/* Now enable the clocks, plane, pipe, and connectors that we set up. */
- for_each_intel_crtc_masked(dev, prepare_pipes, intel_crtc)
+ for_each_intel_crtc_masked(dev, prepare_pipes, intel_crtc) {
+ update_scanline_offset(intel_crtc);
+
dev_priv->display.crtc_enable(&intel_crtc->base);
+ }

/* FIXME: add subpixel order */
done:
@@ -11789,6 +11830,8 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc)
*/
crtc->cpu_fifo_underrun_disabled = true;
crtc->pch_fifo_underrun_disabled = true;
+
+ update_scanline_offset(crtc);
}
}

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 32a74e1..dd562b9 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -403,6 +403,8 @@ struct intel_crtc {
} wm;

wait_queue_head_t vbl_wait;
+
+ int scanline_offset;
};

struct intel_plane_wm_parameters {
--
1.8.3.2