drm/i915: do not update cursor in crtc mode set

The cursor is disabled before crtc mode set in crtc disable (and we
assert this is the case), and enabled afterwards in crtc enable. Do not
update it in crtc mode set.

On HSW enabling a plane on a disabled pipe may hang the entire system.
And there's no good reason for doing it ever, so just don't.

v2: Add note about HSW hangs - vsyrjala

Cc: stable@vger.kernel.org
Suggested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Tested-by: NPaulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_display.c

@@ -4877,9 +4877,6 @@ static int i9xx_crtc_mode_set(struct drm_crtc *crtc,
 		return -EINVAL;
 	}
 
-	/* Ensure that the cursor is valid for the new mode before changing... */
-	intel_crtc_update_cursor(crtc, true);
-
 	if (is_lvds && dev_priv->lvds_downclock_avail) {
 		/*
 		 * Ensure we match the reduced clock's P to the target clock.
@@ -5768,9 +5765,6 @@ static int ironlake_crtc_mode_set(struct drm_crtc *crtc,
 		intel_crtc->config.dpll.p2 = clock.p2;
 	}
 
-	/* Ensure that the cursor is valid for the new mode before changing... */
-	intel_crtc_update_cursor(crtc, true);
-
 	/* CPU eDP is the only output that doesn't need a PCH PLL of its own. */
 	if (intel_crtc->config.has_pch_encoder) {
 		fp = i9xx_dpll_compute_fp(&intel_crtc->config.dpll);
@@ -6260,9 +6254,6 @@ static int haswell_crtc_mode_set(struct drm_crtc *crtc,
 	if (!intel_ddi_pll_mode_set(crtc))
 		return -EINVAL;
 
-	/* Ensure that the cursor is valid for the new mode before changing... */
-	intel_crtc_update_cursor(crtc, true);
-
 	if (intel_crtc->config.has_dp_encoder)
 		intel_dp_set_m_n(intel_crtc);