[Intel-gfx] [PATCH 2/2] drm/i915: Fix clock readout when pipes are enabld w/o ports

[ville.syrjala at linux.intel.com]

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

The BIOS sometimes likes to enable pipes w/o any ports, at least on
older machines. Currently we fail to assign anything sensible to
crtc->hwmode.crtc_clock which leads to complaints from the vblank code.
Deal with active pipes w/o ports and assign something sensible to
crtc_clock.

Gets rid of rest of these on my gen4:
[drm:drm_calc_timestamping_constants [drm]] *ERROR* crtc 24: Can't calculate constants, dotclock = 0!
[drm:i915_get_vblank_timestamp] crtc 1 is disabled

Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index b4229ce..32e9f91 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14857,13 +14857,22 @@ intel_check_plane_mapping(struct intel_crtc *crtc)
 	return true;
 }
 
+static bool intel_crtc_has_encoders(struct intel_crtc *crtc)
+{
+	struct drm_device *dev = crtc->base.dev;
+	struct intel_encoder *encoder;
+
+	for_each_encoder_on_crtc(dev, &crtc->base, encoder)
+		return true;
+
+	return false;
+}
+
 static void intel_sanitize_crtc(struct intel_crtc *crtc)
 {
 	struct drm_device *dev = crtc->base.dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	struct intel_encoder *encoder;
 	u32 reg;
-	bool enable;
 
 	/* Clear any frame start delays used for debugging left by the BIOS */
 	reg = PIPECONF(crtc->config->cpu_transcoder);
@@ -14907,16 +14916,11 @@ static void intel_sanitize_crtc(struct intel_crtc *crtc)
 
 	/* Adjust the state of the output pipe according to whether we
 	 * have active connectors/encoders. */
-	enable = false;
-	for_each_encoder_on_crtc(dev, &crtc->base, encoder) {
-		enable = true;
-		break;
-	}
-
-	if (!enable)
+	if (!intel_crtc_has_encoders(crtc))
 		intel_crtc_disable_noatomic(&crtc->base);
 
 	if (crtc->active != crtc->base.state->active) {
+		struct intel_encoder *encoder;
 
 		/* This can happen either due to bugs in the get_hw_state
 		 * functions or because of calls to intel_crtc_disable_noatomic,
@@ -15180,6 +15184,15 @@ static void intel_modeset_readout_hw_state(struct drm_device *dev)
 	}
 
 	for_each_intel_crtc(dev, crtc) {
+		/* in case the pipe is active w/o any ports */
+		if (crtc->active && !intel_crtc_has_encoders(crtc)) {
+			crtc->config->base.adjusted_mode.crtc_clock =
+				crtc->config->port_clock;
+			if (crtc->config->pixel_multiplier)
+				crtc->config->base.adjusted_mode.crtc_clock /=
+					crtc->config->pixel_multiplier;
+		}
+
 		crtc->base.hwmode = crtc->config->base.adjusted_mode;
 	}
 }
-- 
2.4.6