Ville Syrjälä 64989ca4b2 drm/i915: Refresh cached DP port register value on resume ... During hibernation the cached DP port register value will be left with whatever value we have there when we create the hibernation image. Currently that means the port (and eDP PLL) will be off in the cached value. However when we resume there is no guarantee that the value in the actual register will match the cached value. If i915 isn't loaded in the kernel that loads the hibernation image, the port may well be on (eg. left on by the BIOS). The encoder state readout does the right thing in this case and updates our encoder state to reflect the actual hardware state. However the post-resume modeset will then use the stale cached port register value in intel_dp_link_down() and potentially confuse the hardware. This was caught by the following assert WARNING: CPU: 3 PID: 5288 at ../drivers/gpu/drm/i915/intel_dp.c:2184 assert_edp_pll+0x99/0xa0 [i915] eDP PLL state assertion failure (expected on, current off) on account of the eDP PLL getting prematurely turned off when shutting down the port, since the DP_PLL_ENABLE bit wasn't set in the cached register value. Presumably I introduced this problem in commit 6fec766283 ("drm/i915: Use intel_dp->DP in eDP PLL setup") as before that we didn't update the cached value after shuttting the port down. That's assuming the port got enabled at least once prior to hibernating. If that didn't happen then the cached value would still have been totally out of sync with reality (eg. first boot w/o eDP on, then hibernate, and then resume with eDP on). So, let's fix this properly and refresh the cached register value from the hardware register during resume. DDI platforms shouldn't use the cached value during port disable at least, so shouldn't have this particular issue. They might still have issues if we skip the initial modeset and then try to retrain the link or something. But untangling this DP vs. DDI mess is a bigger topic, so let's jut punt on DDI for now. Cc: Jani Nikula <jani.nikula@intel.com> Cc: stable@vger.kernel.org Fixes: 6fec766283 ("drm/i915: Use intel_dp->DP in eDP PLL setup") Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1463162036-27931-1-git-send-email-ville.syrjala@linux.intel.com Reviewed-by: Imre Deak <imre.deak@intel.com>		2016-06-22 20:49:17 +03:00
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drm	drm/i915: Refresh cached DP port register value on resume	2016-06-22 20:49:17 +03:00
host1x	remove lots of IS_ERR_VALUE abuses	2016-05-27 15:26:11 -07:00
ipu-v3	drm/imx: Match imx-ipuv3-crtc components using device node in platform data	2016-05-23 12:35:11 +02:00
vga	vga_switcheroo: Support deferred probing of audio clients	2016-05-31 13:16:22 +02:00
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