From e16ed265e3aad492d0143a41b22eeb050b3dc60f Mon Sep 17 00:00:00 2001 From: Kai Vehmanen Date: Tue, 31 Dec 2019 16:00:07 +0200 Subject: [PATCH 10/15] drm/i915: Limit audio CDCLK>=2*BCLK constraint back to GLK only Revert changes done in commit f6ec9483091f ("drm/i915: extend audio CDCLK>=2*BCLK constraint to more platforms"). Audio drivers communicate with i915 over HDA bus multiple times during system boot-up and each of these transactions result in matching get_power/put_power calls to i915, and depending on the platform, a modeset change causing visible flicker. GLK is the only platform with minimum CDCLK significantly lower than BCLK, and thus for GLK setting a higher CDCLK is mandatory. For other platforms, minimum CDCLK is close but below 2*BCLK (e.g. on ICL, CDCLK=176.4kHz with BCLK=96kHz). Spec-wise the constraint should be set, but in practise no communication errors have been reported and the downside if set is the flicker observed at boot-time. Revert to old behaviour until better mechanism to manage probe-time clocks is available. The full CDCLK>=2*BCLK constraint is still enforced at pipe enable time in intel_crtc_compute_min_cdclk(). Bugzilla: https://gitlab.freedesktop.org/drm/intel/issues/913 Fixes: f6ec9483091f ("drm/i915: extend audio CDCLK>=2*BCLK constraint to more platforms") Signed-off-by: Kai Vehmanen Reviewed-by: Matt Roper Signed-off-by: Matt Roper Link: https://patchwork.freedesktop.org/patch/msgid/20191231140007.31728-1-kai.vehmanen@linux.intel.com (cherry picked from commit 1ee48a61aa57dbdbc3cd2808d8b28df40d938e44) Signed-off-by: Joonas Lahtinen --- drivers/gpu/drm/i915/display/intel_audio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_audio.c b/drivers/gpu/drm/i915/display/intel_audio.c index 05ef43b13d1c..0cf475f3063c 100644 --- a/drivers/gpu/drm/i915/display/intel_audio.c +++ b/drivers/gpu/drm/i915/display/intel_audio.c @@ -858,7 +858,7 @@ static unsigned long i915_audio_component_get_power(struct device *kdev) } /* Force CDCLK to 2*BCLK as long as we need audio powered. */ - if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv)) + if (IS_GEMINILAKE(dev_priv)) glk_force_audio_cdclk(dev_priv, true); if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv)) @@ -877,7 +877,7 @@ static void i915_audio_component_put_power(struct device *kdev, /* Stop forcing CDCLK to 2*BCLK if no need for audio to be powered. */ if (--dev_priv->audio_power_refcount == 0) - if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv)) + if (IS_GEMINILAKE(dev_priv)) glk_force_audio_cdclk(dev_priv, false); intel_display_power_put(dev_priv, POWER_DOMAIN_AUDIO, cookie); -- 2.25.0