From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> On VLV/CHV there is some kind of linkage between the cdclk frequency and the DP link frequency. The spec says: "For DP audio configuration, cdclk frequency shall be set to meet the following requirements: DP Link Frequency(MHz) | Cdclk frequency(MHz) 270 | 320 or higher 162 | 200 or higher" I suspect that would more accurately be expressed as "cdclk >= DP link clock", and in any case we can express it like that in the code because of the limited set of cdclk and link frequencies we support. Without this we can end up in a situation where the cdclk is too low and enabling DP audio will kill the pipe. Happens eg. with 2560x1440 modes where the 266MHz cdclk is sufficient to pump the pixels (241.5 MHz dotclock) but is too low for the DP audio due to the link frequency being 270 MHz. Cc: stable@xxxxxxxxxxxxxxx Tested-by: Stefan Gottwald <gottwald@xxxxxxxx> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111149 Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/display/intel_cdclk.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_cdclk.c b/drivers/gpu/drm/i915/display/intel_cdclk.c index d0581a1ac243..93b0d190c184 100644 --- a/drivers/gpu/drm/i915/display/intel_cdclk.c +++ b/drivers/gpu/drm/i915/display/intel_cdclk.c @@ -2262,6 +2262,17 @@ int intel_crtc_compute_min_cdclk(const struct intel_crtc_state *crtc_state) if (crtc_state->has_audio && INTEL_GEN(dev_priv) >= 9) min_cdclk = max(2 * 96000, min_cdclk); + /* + * "For DP audio configuration, cdclk frequency shall be set to + * meet the following requirements: + * DP Link Frequency(MHz) | Cdclk frequency(MHz) + * 270 | 320 or higher + * 162 | 200 or higher" + */ + if ((IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) && + intel_crtc_has_dp_encoder(crtc_state) && crtc_state->has_audio) + min_cdclk = max(crtc_state->port_clock, min_cdclk); + /* * On Valleyview some DSI panels lose (v|h)sync when the clock is lower * than 320000KHz. -- 2.21.0
