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drm/i915: Apply a workaround for transitioning from DP on pipe B to HDMI.

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This workaround only applies to Ironlake.

Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@kernel.org
This commit is contained in:
Eric Anholt 2010-11-18 09:32:59 +08:00 • committed by Chris Wilson
commit 5bddd17fec
1 changed files with 21 additions and 0 deletions
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21
drivers/gpu/drm/i915/intel_dp.c
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@ -1374,6 +1374,7 @@ intel_dp_link_down(struct intel_dp *intel_dp)
{
struct drm_device *dev = intel_dp->base.base.dev;
struct drm_i915_private *dev_priv = dev->dev_private;
struct intel_crtc *intel_crtc = to_intel_crtc(intel_dp->base.base.crtc);
uint32_t DP = intel_dp->DP;
DRM_DEBUG_KMS("\n");
@ -1398,6 +1399,26 @@ intel_dp_link_down(struct intel_dp *intel_dp)
if (is_edp(intel_dp))
DP |= DP_LINK_TRAIN_OFF;
if (!HAS_PCH_CPT(dev) && (DP & DP_PIPEB_SELECT)) {
/* Hardware workaround: leaving our transcoder select
* set to transcoder B while it's off will prevent the
* corresponding HDMI output on transcoder A.
*
* Combine this with another hardware workaround:
* transcoder select bit can only be cleared while the
* port is enabled.
*/
DP &= ~DP_PIPEB_SELECT;
I915_WRITE(intel_dp->output_reg, DP);
/* Changes to enable or select take place the vblank
* after being written.
*/
intel_wait_for_vblank(intel_dp->base.base.dev,
intel_crtc->pipe);
}
I915_WRITE(intel_dp->output_reg, DP & ~DP_PORT_EN);
POSTING_READ(intel_dp->output_reg);
}