drm/i915: Put all non-blocking modesets onto an ordered wq (757fffcf) · Commits · e / devices / android_kernel_fairphone_FP4

We have plenty of global registers and whatnot programmed without any further locking by the modeset code. Currently non-bocking modesets are allowed to execute in parallel which could corrupt said registers. To avoid the problem let's run all non-blocking modesets on an ordered workqueue. We still put page flips etc. to system_unbound_wq allowing page flips on one pipe to execute in parallel with page flips or a modeset on a another pipe (assuming no known state is shared between them, at which point they would have been added to the same atomic commit and serialized that way). Blocking modesets are already serialized with each other by connection_mutex, and thus are safe. To serialize them with non-blocking modesets we just flush the workqueue before executing blocking modesets. Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Fixes: ("drm/i915: nonblocking commit") Signed-off-by:

Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20171113133622.8593-1-ville.syrjala@linux.intel.com Acked-by:

Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by:

Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

drivers/gpu/drm/i915/i915_drv.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -1960,6 +1960,9 @@ struct drm_i915_private {
		*/
		struct workqueue_struct *wq;

		/* ordered wq for modesets */
		struct workqueue_struct *modeset_wq;

		/* Display functions */
		struct drm_i915_display_funcs display;

drivers/gpu/drm/i915/intel_display.c

+11 −3

Original line number	Diff line number	Diff line
		@@ -12483,11 +12483,15 @@ static int intel_atomic_commit(struct drm_device *dev,
		INIT_WORK(&state->commit_work, intel_atomic_commit_work);

		i915_sw_fence_commit(&intel_state->commit_ready);
		if (nonblock)
		if (nonblock && intel_state->modeset) {
		queue_work(dev_priv->modeset_wq, &state->commit_work);
		} else if (nonblock) {
		queue_work(system_unbound_wq, &state->commit_work);
		else
		} else {
		if (intel_state->modeset)
		flush_workqueue(dev_priv->modeset_wq);
		intel_atomic_commit_tail(state);

		}

		return 0;
		}
		@@ -14450,6 +14454,8 @@ int intel_modeset_init(struct drm_device *dev)
		enum pipe pipe;
		struct intel_crtc *crtc;

		dev_priv->modeset_wq = alloc_ordered_workqueue("i915_modeset", 0);

		drm_mode_config_init(dev);

		dev->mode_config.min_width = 0;
		@@ -15254,6 +15260,8 @@ void intel_modeset_cleanup(struct drm_device *dev)
		intel_cleanup_gt_powersave(dev_priv);

		intel_teardown_gmbus(dev_priv);

		destroy_workqueue(dev_priv->modeset_wq);
		}

		void intel_connector_attach_encoder(struct intel_connector *connector,