From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> On GLK CDCLK frequency needs to be at least 2*96 MHz when accessing the audio hardware. Currently we bump the CDCLK frequency up temporarily (if not high enough already) whenever audio hardware is being accessed, and drop it back down afterwards. With a single active pipe this works just fine as we can switch between all the valid CDCLK frequencies by changing the cd2x divider, which doesn't require a full modeset. However with multiple active pipes the cd2x divider trick no longer works, and thus we end up blinking all displays off and back on. To avoid this let's just bump the CDCLK frequency to >=2*96MHz whenever multiple pipes are active. The downside is slightly higher power consumption, but that seems like an acceptable tradeoff. With a single active pipe we can stick to the current more optiomal (from power comsumption POV) behaviour. Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9599 Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/display/intel_cdclk.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c index 6d7ba4d0f130..3ddf4201e224 100644 --- a/drivers/gpu/drm/i915/display/intel_cdclk.c +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c @@ -2750,6 +2750,18 @@ static int intel_compute_min_cdclk(struct intel_cdclk_state *cdclk_state) for_each_pipe(dev_priv, pipe) min_cdclk = max(cdclk_state->min_cdclk[pipe], min_cdclk); + /* + * Avoid glk_force_audio_cdclk() causing excessive screen + * blinking when multiple pipes are active by making sure + * cdclk frequency is always high enough for audio. With a + * single active pipe we can always change CDCLK frequency + * by changing the cd2x divider (see glk_cdclk_table[]) and + * thus a full modeset won't be needed then. + */ + if (DISPLAY_VER(dev_priv) == 10 && cdclk_state->active_pipes && + !is_power_of_2(cdclk_state->active_pipes)) + min_cdclk = max(2 * 96000, min_cdclk); + if (min_cdclk > dev_priv->display.cdclk.max_cdclk_freq) { drm_dbg_kms(&dev_priv->drm, "required cdclk (%d kHz) exceeds max (%d kHz)\n", -- 2.41.0
