According to the bspec, when set M/N, should disable
and enable transcoder which attaching DP audio. However
the implementation will affect performance much more.
Therefore, only KBL changed to use automatic M/N.
Testing:
DP audio testing on SKL/KBL works (MP4, speaker test case).
no audio delay in multiple resolution including 4K.
Signed-off-by: Quanxian Wang <quanxian.wang@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_audio.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_audio.c b/drivers/gpu/drm/i915/intel_audio.c
index d805b6e..ba4994e 100644
--- a/drivers/gpu/drm/i915/intel_audio.c
+++ b/drivers/gpu/drm/i915/intel_audio.c
@@ -289,6 +289,10 @@ hsw_dp_audio_config_update(struct intel_crtc *intel_crtc, enum port port,
enum pipe pipe = intel_crtc->pipe;
u32 tmp;
+ /* It doesn't work on KBL and uses automatic M/N. */
+ if (IS_KABYLAKE(dev_priv))
+ nm = NULL;
+
if (nm)
DRM_DEBUG_KMS("using Maud %u, Naud %u\n", nm->m, nm->n);
else
--
2.5.0
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