[ Upstream commit a8f196a0fa6391a436f63f360a1fb57031fdf26c ]
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 (200, 266, 320, 400 MHz) and link frequencies (162 and 270 MHz) 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.
v2: Spell out the cdclk and link frequencies we actually support
Cc: stable@vger.kernel.org Tested-by: Stefan Gottwald gottwald@igel.com Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111149 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20190717114536.22937-1-ville.s... Acked-by: Chris Wilson chris@chris-wilson.co.uk (cherry picked from commit bffb31f73b29a60ef693842d8744950c2819851d) Signed-off-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/i915/intel_cdclk.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c index ae40a8679314e..fd5236da039fb 100644 --- a/drivers/gpu/drm/i915/intel_cdclk.c +++ b/drivers/gpu/drm/i915/intel_cdclk.c @@ -2269,6 +2269,17 @@ 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.