drm/atomic-helper: Remove legacy backoff hack from gamma_set

Another one knocked down.

With this we can also remove the temporary hack in the gamma_set
ioctl.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170403083304.9083-14-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_atomic_helper.c

@@ -3519,8 +3519,7 @@ int drm_atomic_helper_legacy_gamma_set(struct drm_crtc *crtc,
 		blob_data[i].blue = blue[i];
 	}
 
-	state->acquire_ctx = crtc->dev->mode_config.acquire_ctx;
-retry:
+	state->acquire_ctx = ctx;
 	crtc_state = drm_atomic_get_crtc_state(state, crtc);
 	if (IS_ERR(crtc_state)) {
 		ret = PTR_ERR(crtc_state);
@@ -3544,18 +3543,10 @@ retry:
 		goto fail;
 
 	ret = drm_atomic_commit(state);
-fail:
-	if (ret == -EDEADLK)
-		goto backoff;
 
+fail:
 	drm_atomic_state_put(state);
 	drm_property_blob_put(blob);
 	return ret;
-
-backoff:
-	drm_atomic_state_clear(state);
-	drm_atomic_legacy_backoff(state);
-
-	goto retry;
 }
 EXPORT_SYMBOL(drm_atomic_helper_legacy_gamma_set);

drivers/gpu/drm/drm_color_mgmt.c

@@ -236,7 +236,6 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 		return -EINVAL;
 
 	drm_modeset_acquire_init(&ctx, 0);
-	dev->mode_config.acquire_ctx = &ctx;
 retry:
 	ret = drm_modeset_lock_all_ctx(dev, &ctx);
 	if (ret)