From: Ville Syrjälä Date: Wed, 3 Jun 2015 12:45:11 +0000 (+0300) Subject: drm/i915: Don't enable IPS when pixel rate exceeds 95% X-Git-Tag: omap-for-v4.3/fixes-rc1~89^2~36^2~307^2~11 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8cfb340774744438dea08a32072bea4a162dd132;p=pandora-kernel.git drm/i915: Don't enable IPS when pixel rate exceeds 95% Bspec says we shouldn't enable IPS on BDW when the pipe pixel rate exceeds 95% of the core display clock. Apparently this can cause underruns. There's no similar restriction listed for HSW, so leave that one alone for now. v2: Add pipe_config_supports_ips() (Chris) v3: Compare against the max cdclk insted of the current cdclk v4: Rebased to the latest v5: Rebased to the latest v6: Fix for patch style problems Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=83497 Tested-by: Timo Aaltonen Signed-off-by: Ville Syrjälä Signed-off-by: Mika Kahola Reviewed-by: Damien Lespiau Signed-off-by: Jani Nikula --- diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 445385dd062a..c3f01aa9b510 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -6610,12 +6610,38 @@ retry: return ret; } +static bool pipe_config_supports_ips(struct drm_i915_private *dev_priv, + struct intel_crtc_state *pipe_config) +{ + if (pipe_config->pipe_bpp > 24) + return false; + + /* HSW can handle pixel rate up to cdclk? */ + if (IS_HASWELL(dev_priv->dev)) + return true; + + /* + * FIXME if we compare against max we should then + * increase the cdclk frequency when the current + * value is too low. The other option is to compare + * against the cdclk frequency we're going have post + * modeset (ie. one we computed using other constraints). + * Need to measure whether using a lower cdclk w/o IPS + * is better or worse than a higher cdclk w/ IPS. + */ + return ilk_pipe_pixel_rate(pipe_config) <= + dev_priv->max_cdclk_freq * 95 / 100; +} + static void hsw_compute_ips_config(struct intel_crtc *crtc, struct intel_crtc_state *pipe_config) { + struct drm_device *dev = crtc->base.dev; + struct drm_i915_private *dev_priv = dev->dev_private; + pipe_config->ips_enabled = i915.enable_ips && - hsw_crtc_supports_ips(crtc) && - pipe_config->pipe_bpp <= 24; + hsw_crtc_supports_ips(crtc) && + pipe_config_supports_ips(dev_priv, pipe_config); } static int intel_crtc_compute_config(struct intel_crtc *crtc, Reading git-diff-tree failed