drm/crtc_helper: replace modeset fail path with something simpler

- The previous system was not very transparent, nor flexible.
- This is needed to be able to fix a few bugs in the mechanism.

Signed-off-by: Maarten Maathuis <madman2003@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 54 insertions, 32 deletions

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index a06c5f52c289..a3837b39bb8f 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -704,13 +704,12 @@ EXPORT_SYMBOL(drm_crtc_helper_set_mode);
 int drm_crtc_helper_set_config(struct drm_mode_set *set)
 {
         struct drm_device *dev;
-        struct drm_crtc **save_crtcs, *new_crtc;
-        struct drm_encoder **save_encoders, *new_encoder;
+        struct drm_crtc *save_crtcs, *new_crtc, *crtc;
+        struct drm_encoder *save_encoders, *new_encoder, *encoder;
         struct drm_framebuffer *old_fb = NULL;
-        bool save_enabled;
         bool mode_changed = false; /* if true do a full mode set */
         bool fb_changed = false; /* if true and !mode_changed just do a flip */
-        struct drm_connector *connector;
+        struct drm_connector *save_connectors, *connector;
         int count = 0, ro, fail = 0;
         struct drm_crtc_helper_funcs *crtc_funcs;
         int ret = 0;
@@ -735,25 +734,47 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
 
         dev = set->crtc->dev;
 
-        /* save previous config */
-        save_enabled = set->crtc->enabled;
-
-        /*
-         * We do mode_config.num_connectors here since we'll look at the
-         * CRTC and encoder associated with each connector later.
-         */
-        save_crtcs = kzalloc(dev->mode_config.num_connector *
-                             sizeof(struct drm_crtc *), GFP_KERNEL);
+        /* Allocate space for the backup of all (non-pointer) crtc, encoder and
+         * connector data. */
+        save_crtcs = kzalloc(dev->mode_config.num_crtc *
+                             sizeof(struct drm_crtc), GFP_KERNEL);
         if (!save_crtcs)
                 return -ENOMEM;
 
-        save_encoders = kzalloc(dev->mode_config.num_connector *
-                                sizeof(struct drm_encoders *), GFP_KERNEL);
+        save_encoders = kzalloc(dev->mode_config.num_encoder *
+                                sizeof(struct drm_encoder), GFP_KERNEL);
         if (!save_encoders) {
                 kfree(save_crtcs);
                 return -ENOMEM;
         }
 
+        save_connectors = kzalloc(dev->mode_config.num_connector *
+                                sizeof(struct drm_connector), GFP_KERNEL);
+        if (!save_connectors) {
+                kfree(save_crtcs);
+                kfree(save_encoders);
+                return -ENOMEM;
+        }
+
+        /* Copy data. Note that driver private data is not affected.
+         * Should anything bad happen only the expected state is
+         * restored, not the drivers personal bookkeeping.
+         */
+        count = 0;
+        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+                save_crtcs[count++] = *crtc;
+        }
+
+        count = 0;
+        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+                save_encoders[count++] = *encoder;
+        }
+
+        count = 0;
+        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+                save_connectors[count++] = *connector;
+        }
+
         /* We should be able to check here if the fb has the same properties
          * and then just flip_or_move it */
         if (set->crtc->fb != set->fb) {
@@ -786,7 +807,6 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
         list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                 struct drm_connector_helper_funcs *connector_funcs =
                         connector->helper_private;
-                save_encoders[count++] = connector->encoder;
                 new_encoder = connector->encoder;
                 for (ro = 0; ro < set->num_connectors; ro++) {
                         if (set->connectors[ro] == connector) {
@@ -809,7 +829,7 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
 
         if (fail) {
                 ret = -EINVAL;
-                goto fail_no_encoder;
+                goto fail;
         }
 
         count = 0;
@@ -817,8 +837,6 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
                 if (!connector->encoder)
                         continue;
 
-                save_crtcs[count++] = connector->encoder->crtc;
-
                 if (connector->encoder->crtc == set->crtc)
                         new_crtc = NULL;
                 else
@@ -833,7 +851,7 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
                 if (new_crtc &&
                     !drm_encoder_crtc_ok(connector->encoder, new_crtc)) {
                         ret = -EINVAL;
-                        goto fail_set_mode;
+                        goto fail;
                 }
                 if (new_crtc != connector->encoder->crtc) {
                         DRM_DEBUG_KMS("crtc changed, full mode switch\n");
@@ -862,7 +880,7 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
                                 DRM_ERROR("failed to set mode on crtc %p\n",
                                           set->crtc);
                                 ret = -EINVAL;
-                                goto fail_set_mode;
+                                goto fail;
                         }
                         /* TODO are these needed? */
                         set->crtc->desired_x = set->x;
@@ -877,30 +895,34 @@ int drm_crtc_helper_set_config(struct drm_mode_set *set)
                 ret = crtc_funcs->mode_set_base(set->crtc,
                                                 set->x, set->y, old_fb);
                 if (ret != 0)
-                    goto fail_set_mode;
+                        goto fail;
         }
 
+        kfree(save_connectors);
         kfree(save_encoders);
         kfree(save_crtcs);
         return 0;
 
-fail_set_mode:
-        set->crtc->enabled = save_enabled;
-        set->crtc->fb = old_fb;
+fail:
+        /* Restore all previous data. */
         count = 0;
-        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
-                if (!connector->encoder)
-                        continue;
+        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
+                *crtc = save_crtcs[count++];
+        }
 
-                connector->encoder->crtc = save_crtcs[count++];
+        count = 0;
+        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
+                *encoder = save_encoders[count++];
         }
-fail_no_encoder:
-        kfree(save_crtcs);
+
         count = 0;
         list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
-                connector->encoder = save_encoders[count++];
+                *connector = save_connectors[count++];
         }
+
+        kfree(save_connectors);
         kfree(save_encoders);
+        kfree(save_crtcs);
         return ret;
 }
 EXPORT_SYMBOL(drm_crtc_helper_set_config);