[Intel-gfx] [PATCH v4 2/2] drm/i915/dp: Extend BDW DP audio workaround to GEN9 platforms

[Dhinakaran Pandiyan]

According to BSpec, cdclk for BDW has to be not less than 432 MHz with DP
audio enabled, port width x4, and link rate HBR2 (5.4 GHz). With cdclk less
than 432 MHz, enabling audio leads to pipe FIFO underruns and displays
cycling on/off.

Let's apply this work around to GEN9 platforms too, as it fixes the same
issue.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97907
Cc: stable at vger.kernel.org
Cc: Libin Yang <libin.yang at linux.intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 37483ee..c0ae147 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10264,8 +10264,10 @@ static void bxt_modeset_commit_cdclk(struct drm_atomic_state *old_state)
 static int bdw_adjust_min_pipe_pixel_rate(struct intel_crtc_state *crtc_state,
 					  int pixel_rate)
 {
+	struct drm_device *dev = crtc_state->base.crtc->dev;
+
 	/* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
-	if (crtc_state->ips_enabled)
+	if (IS_BROADWELL(to_i915(dev)) && crtc_state->ips_enabled)
 		pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95);
 
 	/* BSpec says "Do not use DisplayPort with CDCLK less than
@@ -10307,7 +10309,7 @@ static int ilk_max_pixel_rate(struct drm_atomic_state *state)
 
 		pixel_rate = ilk_pipe_pixel_rate(crtc_state);
 
-		if (IS_BROADWELL(dev_priv))
+		if (IS_BROADWELL(dev_priv) || IS_GEN9(dev_priv))
 			pixel_rate = bdw_adjust_min_pipe_pixel_rate(crtc_state,
 								    pixel_rate);
 
-- 
2.7.4