[PATCH v3 2/6] drm/amd/display/amdgpu_dm: Refactor register_backlight_device()

[Hans de Goede]

Refactor register_backlight_device():

1) Turn the connector-type + signal check into an early exit
condition to avoid the indentation level of the rest of the code

2) Add an array bounds check for the arrays indexed by dm->num_of_edps

3) register_backlight_device() always increases dm->num_of_edps if
amdgpu_dm_register_backlight_device() has assigned a backlight_dev to
the current dm->backlight_link[dm->num_of_edps] slot.

So on its next call dm->backlight_dev[dm->num_of_edps] always point to
the next empty slot and the "if (!dm->backlight_dev[dm->num_of_edps])"
check will thus always succeed and can be removed.

4) Add a bl_idx local variable to use as array index, rather then
using dm->num_of_edps to improve the code readability.

Signed-off-by: Hans de Goede <hdego...@redhat.com>
---
 .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 28 ++++++++++---------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 42b88ab5552d..1b5efa56ec15 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4231,21 +4231,23 @@ static int initialize_plane(struct 
amdgpu_display_manager *dm,
 static void register_backlight_device(struct amdgpu_display_manager *dm,
                                      struct dc_link *link)
 {
-       if ((link->connector_signal & (SIGNAL_TYPE_EDP | SIGNAL_TYPE_LVDS)) &&
-           link->type != dc_connection_none) {
-               /*
-                * Event if registration failed, we should continue with
-                * DM initialization because not having a backlight control
-                * is better then a black screen.
-                */
-               if (!dm->backlight_dev[dm->num_of_edps])
-                       amdgpu_dm_register_backlight_device(dm);
+       int bl_idx = dm->num_of_edps;
 
-               if (dm->backlight_dev[dm->num_of_edps]) {
-                       dm->backlight_link[dm->num_of_edps] = link;
-                       dm->num_of_edps++;
-               }
+       if (!(link->connector_signal & (SIGNAL_TYPE_EDP | SIGNAL_TYPE_LVDS)) ||
+           link->type == dc_connection_none)
+               return;
+
+       if (dm->num_of_edps >= AMDGPU_DM_MAX_NUM_EDP) {
+               drm_warn(adev_to_drm(dm->adev), "Too much eDP connections, 
skipping backlight setup for additional eDPs\n");
+               return;
        }
+
+       amdgpu_dm_register_backlight_device(dm);
+       if (!dm->backlight_dev[bl_idx])
+               return;
+
+       dm->backlight_link[bl_idx] = link;
+       dm->num_of_edps++;
 }
 
 static void amdgpu_set_panel_orientation(struct drm_connector *connector);
-- 
2.39.1