[Intel-gfx] [PATCH 2/2] drm/i915: Implement BXT and GLK cdclk restriction based on Azalia BCLK

[Dhinakaran Pandiyan]

According to BSpec, "The CD clock frequency must be at least twice the
frequency of the Azalia BCLK." and BCLK is configured to 96 MHz by
default. BXT and GLK both have cdclk frequencies that are less han 192 MHz,
so apply the check conditionally for these platforms.

Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/i915/intel_cdclk.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
index 8fc0f72..89027fa 100644
--- a/drivers/gpu/drm/i915/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/intel_cdclk.c
@@ -1444,6 +1444,8 @@ static int intel_min_cdclk(struct drm_atomic_state *state)
 		struct intel_crtc_state *crtc_state;
 
 		crtc_state = to_intel_crtc_state(cstate);
+		if (!crtc_state->has_audio)
+			continue;
 
 		/* According to BSpec, "Do not use DisplayPort with CDCLK less
 		 * than 432 MHz, audio enabled, port width x4, and link rate
@@ -1452,7 +1454,6 @@ static int intel_min_cdclk(struct drm_atomic_state *state)
 		 * for GLK is at 316.8 MHz
 		 */
 		if (intel_crtc_has_dp_encoder(crtc_state) &&
-		    crtc_state->has_audio &&
 		    crtc_state->port_clock >= 540000 &&
 		    crtc_state->lane_count == 4) {
 			if (IS_GEMINILAKE(dev_priv))
@@ -1460,6 +1461,13 @@ static int intel_min_cdclk(struct drm_atomic_state *state)
 			else if (IS_BROADWELL(dev_priv) || IS_GEN9(dev_priv))
 				min_cdclk = 432000;
 		}
+
+		/* According to BSpec, "The CD clock frequency must be at least
+		 * twice the frequency of the Azalia BCLK." and BCLK is 96 MHz
+		 * by default.
+		 */
+		if (IS_BROXTON(dev_priv) || IS_GEMINILAKE(dev_priv))
+			min_cdclk = max(min_cdclk, 2 * 96000);
 	}
 
 	return min_cdclk;
-- 
2.7.4