From: Paulo Zanoni Date: Thu, 19 Sep 2013 20:03:06 +0000 (-0300) Subject: drm/i915: wait for IPS_ENABLE when enabling IPS X-Git-Tag: v3.13-rc1~76^2~68^2~88 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5ade2c2f5813733f23bbb2f21e8ba5c3f8474a2b;p=pandora-kernel.git drm/i915: wait for IPS_ENABLE when enabling IPS At the end of haswell_crtc_enable we have an intel_wait_for_vblank with a big comment, and the message suggests it's a workaround for something we don't really understand. So I removed that wait and started getting HW state readout error messages saying that the IPS state is not what we expected. I investigated and concluded that after you write IPS_ENABLE to IPS_CTL, the bit will only actually become 1 on the next vblank. So add code to wait for the IPS_ENABLE bit. We don't really need this wait right now due to the wait I already mentioned, but at least this one has a reason to be there, while the other one is just to workaround some problem: we may remove it in the future. The wait also acts as a POSTING_READ which we missed. Signed-off-by: Paulo Zanoni Reviewed-by: Chris Wilson Signed-off-by: Daniel Vetter --- Reading git-diff-tree failed