gnu: linux-libre: Fix drm_wait_one_vblank warnings.

* gnu/packages/patches/linux-libre-vblank-fix.patch: New file.
* gnu-system.am (dist_patch_DATA): Add it.
* gnu/packages/linux.scm (linux-libre)[source]: Add patch.

gnu-system.am

@@ -468,6 +468,7 @@ dist_patch_DATA =						\
   gnu/packages/patches/libvpx-fix-ssse3-quantize.patch		\
   gnu/packages/patches/libvpx-vp9-out-of-bounds-access.patch	\
   gnu/packages/patches/linux-libre-libreboot-fix.patch		\
+  gnu/packages/patches/linux-libre-vblank-fix.patch		\
   gnu/packages/patches/lirc-localstatedir.patch			\
   gnu/packages/patches/lm-sensors-hwmon-attrs.patch		\
   gnu/packages/patches/lua51-liblua-so.patch                    \

gnu/packages/linux.scm

@@ -273,7 +273,8 @@ for SYSTEM, or #f if there is no configuration for SYSTEM."
               (base32
                "13nq0wzkjy7hrhnnvxlwzs1awlqd81vzriqddjn6s9ma3fzj44bn"))
              (patches
-              (list (search-patch "linux-libre-libreboot-fix.patch")))))
+              (list (search-patch "linux-libre-libreboot-fix.patch")
+                    (search-patch "linux-libre-vblank-fix.patch")))))
     (build-system gnu-build-system)
     (native-inputs `(("perl" ,perl)
                      ("bc" ,bc)

gnu/packages/patches/linux-libre-vblank-fix.patch

@@ -0,0 +1,175 @@
+From f9b61ff6bce9a44555324b29e593fdffc9a115bc Mon Sep 17 00:00:00 2001
+From: Daniel Vetter <daniel.vetter@ffwll.ch>
+Date: Wed, 7 Jan 2015 13:54:39 +0100
+Subject: [PATCH] drm/i915: Push vblank enable/disable past
+ encoder->enable/disable
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+It is platform/output depenedent when exactly the pipe will start
+running. Sometimes we just need the (cpu) pipe enabled, in other cases
+the pch transcoder is enough and in yet other cases the (DP) port is
+sending the frame start signal.
+
+In a perfect world we'd put the drm_crtc_vblank_on call exactly where
+the pipe starts running, but due to cloning and similar things this
+will get messy. And the current approach of picking the most
+conservative place for all combinations also doesn't work since that
+results in legit vblank waits (in encoder->enable hooks, e.g. the 2
+vblank waits for sdvo) failing.
+
+Completely going back to the old world before
+
+commit 51e31d49c89055299e34b8f44d13f70e19aaaad1
+Author: Daniel Vetter <daniel.vetter@ffwll.ch>
+Date:   Mon Sep 15 12:36:02 2014 +0200
+
+    drm/i915: Use generic vblank wait
+
+isn't great either since screaming when the vblank wait work because
+the pipe is off is kinda nice.
+
+Pick a compromise and move the drm_crtc_vblank_on right before the
+encoder->enable call. This is a lie on some outputs/platforms, but
+after the ->enable callback the pipe is guaranteed to run everywhere.
+So not that bad really. Suggested by Ville.
+
+v2: Same treatment for drm_crtc_vblank_off and encoder->disable: I've
+missed the ibx pipe B select w/a, which also has a vblank wait in the
+disable function (while the pipe is obviously still running).
+
+Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
+Cc: Chris Wilson <chris@chris-wilson.co.uk>
+Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
+Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
+---
+ drivers/gpu/drm/i915/intel_display.c | 42 ++++++++++++++++++------------------
+ 1 file changed, 21 insertions(+), 21 deletions(-)
+
+diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
+index a1dbe74..e224820 100644
+--- a/drivers/gpu/drm/i915/intel_display.c
++++ b/drivers/gpu/drm/i915/intel_display.c
+@@ -4301,15 +4301,15 @@ static void ironlake_crtc_enable(struct drm_crtc *crtc)
+ 	if (intel_crtc->config.has_pch_encoder)
+ 		ironlake_pch_enable(crtc);
+ 
++	assert_vblank_disabled(crtc);
++	drm_crtc_vblank_on(crtc);
++
+ 	for_each_encoder_on_crtc(dev, crtc, encoder)
+ 		encoder->enable(encoder);
+ 
+ 	if (HAS_PCH_CPT(dev))
+ 		cpt_verify_modeset(dev, intel_crtc->pipe);
+ 
+-	assert_vblank_disabled(crtc);
+-	drm_crtc_vblank_on(crtc);
+-
+ 	intel_crtc_enable_planes(crtc);
+ }
+ 
+@@ -4421,14 +4421,14 @@ static void haswell_crtc_enable(struct drm_crtc *crtc)
+ 	if (intel_crtc->config.dp_encoder_is_mst)
+ 		intel_ddi_set_vc_payload_alloc(crtc, true);
+ 
++	assert_vblank_disabled(crtc);
++	drm_crtc_vblank_on(crtc);
++
+ 	for_each_encoder_on_crtc(dev, crtc, encoder) {
+ 		encoder->enable(encoder);
+ 		intel_opregion_notify_encoder(encoder, true);
+ 	}
+ 
+-	assert_vblank_disabled(crtc);
+-	drm_crtc_vblank_on(crtc);
+-
+ 	/* If we change the relative order between pipe/planes enabling, we need
+ 	 * to change the workaround. */
+ 	haswell_mode_set_planes_workaround(intel_crtc);
+@@ -4479,12 +4479,12 @@ static void ironlake_crtc_disable(struct drm_crtc *crtc)
+ 
+ 	intel_crtc_disable_planes(crtc);
+ 
+-	drm_crtc_vblank_off(crtc);
+-	assert_vblank_disabled(crtc);
+-
+ 	for_each_encoder_on_crtc(dev, crtc, encoder)
+ 		encoder->disable(encoder);
+ 
++	drm_crtc_vblank_off(crtc);
++	assert_vblank_disabled(crtc);
++
+ 	if (intel_crtc->config.has_pch_encoder)
+ 		intel_set_pch_fifo_underrun_reporting(dev_priv, pipe, false);
+ 
+@@ -4544,14 +4544,14 @@ static void haswell_crtc_disable(struct drm_crtc *crtc)
+ 
+ 	intel_crtc_disable_planes(crtc);
+ 
+-	drm_crtc_vblank_off(crtc);
+-	assert_vblank_disabled(crtc);
+-
+ 	for_each_encoder_on_crtc(dev, crtc, encoder) {
+ 		intel_opregion_notify_encoder(encoder, false);
+ 		encoder->disable(encoder);
+ 	}
+ 
++	drm_crtc_vblank_off(crtc);
++	assert_vblank_disabled(crtc);
++
+ 	if (intel_crtc->config.has_pch_encoder)
+ 		intel_set_pch_fifo_underrun_reporting(dev_priv, TRANSCODER_A,
+ 						      false);
+@@ -5021,12 +5021,12 @@ static void valleyview_crtc_enable(struct drm_crtc *crtc)
+ 	intel_update_watermarks(crtc);
+ 	intel_enable_pipe(intel_crtc);
+ 
+-	for_each_encoder_on_crtc(dev, crtc, encoder)
+-		encoder->enable(encoder);
+-
+ 	assert_vblank_disabled(crtc);
+ 	drm_crtc_vblank_on(crtc);
+ 
++	for_each_encoder_on_crtc(dev, crtc, encoder)
++		encoder->enable(encoder);
++
+ 	intel_crtc_enable_planes(crtc);
+ 
+ 	/* Underruns don't raise interrupts, so check manually. */
+@@ -5082,12 +5082,12 @@ static void i9xx_crtc_enable(struct drm_crtc *crtc)
+ 	intel_update_watermarks(crtc);
+ 	intel_enable_pipe(intel_crtc);
+ 
+-	for_each_encoder_on_crtc(dev, crtc, encoder)
+-		encoder->enable(encoder);
+-
+ 	assert_vblank_disabled(crtc);
+ 	drm_crtc_vblank_on(crtc);
+ 
++	for_each_encoder_on_crtc(dev, crtc, encoder)
++		encoder->enable(encoder);
++
+ 	intel_crtc_enable_planes(crtc);
+ 
+ 	/*
+@@ -5159,12 +5159,12 @@ static void i9xx_crtc_disable(struct drm_crtc *crtc)
+ 	 */
+ 	intel_wait_for_vblank(dev, pipe);
+ 
+-	drm_crtc_vblank_off(crtc);
+-	assert_vblank_disabled(crtc);
+-
+ 	for_each_encoder_on_crtc(dev, crtc, encoder)
+ 		encoder->disable(encoder);
+ 
++	drm_crtc_vblank_off(crtc);
++	assert_vblank_disabled(crtc);
++
+ 	intel_disable_pipe(intel_crtc);
+ 
+ 	i9xx_pfit_disable(intel_crtc);
+-- 
+2.2.1
+