drm: Add drm_atomic_set_mode_for_crtc

Add a new helper, to be used later for blob property management, that
sets the mode for a CRTC state, as well as updating the CRTC enable/active
state at the same time.

v2: Do not touch active/mode_changed in CRTC state. Document return
    value. Remove stray drm_atomic_set_mode_prop_for_crtc declaration.

v3: Remove i915 changes, and leave it directly bashing crtc_state->mode
    for the meantime.

Signed-off-by: Daniel Stone <daniels@collabora.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

4 files changed, 50 insertions, 5 deletions

diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 3134f506b762..e749287390a3 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -290,6 +290,42 @@ drm_atomic_get_crtc_state(struct drm_atomic_state *state,
 EXPORT_SYMBOL(drm_atomic_get_crtc_state);
 
 /**
+ * drm_atomic_set_mode_for_crtc - set mode for CRTC
+ * @state: the CRTC whose incoming state to update
+ * @mode: kernel-internal mode to use for the CRTC, or NULL to disable
+ *
+ * Set a mode (originating from the kernel) on the desired CRTC state. Does
+ * not change any other state properties, including enable, active, or
+ * mode_changed.
+ *
+ * RETURNS:
+ * Zero on success, error code on failure. Cannot return -EDEADLK.
+ */
+int drm_atomic_set_mode_for_crtc(struct drm_crtc_state *state,
+                                 struct drm_display_mode *mode)
+{
+        /* Early return for no change. */
+        if (mode && memcmp(&state->mode, mode, sizeof(*mode)) == 0)
+                return 0;
+
+        if (mode) {
+                drm_mode_copy(&state->mode, mode);
+                state->enable = true;
+                DRM_DEBUG_ATOMIC("Set [MODE:%s] for CRTC state %p\n",
+                                 mode->name, state);
+        } else {
+                memset(&state->mode, 0, sizeof(state->mode));
+                state->enable = false;
+                DRM_DEBUG_ATOMIC("Set [NOMODE] for CRTC state %p\n",
+                                 state);
+        }
+
+        return 0;
+}
+EXPORT_SYMBOL(drm_atomic_set_mode_for_crtc);
+
+
+/**
  * drm_atomic_crtc_set_property - set property on CRTC
  * @crtc: the drm CRTC to set a property on
  * @state: the state object to update with the new property value
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index a64bacdcf263..e69d4847e237 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -1607,7 +1607,10 @@ retry:
                 WARN_ON(set->fb);
                 WARN_ON(set->num_connectors);
 
-                crtc_state->enable = false;
+                ret = drm_atomic_set_mode_for_crtc(crtc_state, NULL);
+                if (ret != 0)
+                        goto fail;
+
                 crtc_state->active = false;
 
                 ret = drm_atomic_set_crtc_for_plane(primary_state, NULL);
@@ -1622,9 +1625,11 @@ retry:
         WARN_ON(!set->fb);
         WARN_ON(!set->num_connectors);
 
-        crtc_state->enable = true;
+        ret = drm_atomic_set_mode_for_crtc(crtc_state, set->mode);
+        if (ret != 0)
+                goto fail;
+
         crtc_state->active = true;
-        drm_mode_copy(&crtc_state->mode, set->mode);
 
         ret = drm_atomic_set_crtc_for_plane(primary_state, crtc);
         if (ret != 0)
diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 9297a61a7c95..393114df88a3 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -937,10 +937,11 @@ int drm_helper_crtc_mode_set(struct drm_crtc *crtc, struct drm_display_mode *mod
                         crtc_state->crtc = crtc;
         }
 
-        crtc_state->enable = true;
         crtc_state->planes_changed = true;
         crtc_state->mode_changed = true;
-        drm_mode_copy(&crtc_state->mode, mode);
+        ret = drm_atomic_set_mode_for_crtc(crtc_state, mode);
+        if (ret)
+                goto out;
         drm_mode_copy(&crtc_state->adjusted_mode, adjusted_mode);
 
         if (crtc_funcs->atomic_check) {
diff --git a/include/drm/drm_atomic.h b/include/drm/drm_atomic.h
index e89db0c377ba..1e8c61f23294 100644
--- a/include/drm/drm_atomic.h
+++ b/include/drm/drm_atomic.h
@@ -110,6 +110,9 @@ drm_atomic_get_existing_connector_state(struct drm_atomic_state *state,
 }
 
 int __must_check
+drm_atomic_set_mode_for_crtc(struct drm_crtc_state *state,
+                             struct drm_display_mode *mode);
+int __must_check
 drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
                               struct drm_crtc *crtc);
 void drm_atomic_set_fb_for_plane(struct drm_plane_state *plane_state,