drm/tilcdc: panel: Fix backlight devicetree support

The current backlight support is broken; the driver expects a backlight-class
in the panel devicetree node. Fix this by implementing it properly, getting
an optional backlight from a phandle.

This shouldn't cause any backward-compatibility DT issue because the current
implementation doesn't work and is not even documented.

Tested-by: Darren Etheridge <detheridge@ti.com>
Tested-by: Johannes Pointner <johannes.pointner@br-automation.com>
Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 18 insertions, 5 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_panel.c b/drivers/gpu/drm/tilcdc/tilcdc_panel.c
index c716c128ded2..3dcf08e4dc91 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_panel.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_panel.c
@@ -342,7 +342,7 @@ static struct tilcdc_panel_info *of_get_panel_info(struct device_node *np)
 
 static int panel_probe(struct platform_device *pdev)
 {
-        struct device_node *node = pdev->dev.of_node;
+        struct device_node *bl_node, *node = pdev->dev.of_node;
         struct panel_module *panel_mod;
         struct tilcdc_module *mod;
         struct pinctrl *pinctrl;
@@ -358,6 +358,17 @@ static int panel_probe(struct platform_device *pdev)
         if (!panel_mod)
                 return -ENOMEM;
 
+        bl_node = of_parse_phandle(node, "backlight", 0);
+        if (bl_node) {
+                panel_mod->backlight = of_find_backlight_by_node(bl_node);
+                of_node_put(bl_node);
+
+                if (!panel_mod->backlight)
+                        return -EPROBE_DEFER;
+
+                dev_info(&pdev->dev, "found backlight\n");
+        }
+
         mod = &panel_mod->base;
         pdev->dev.platform_data = mod;
 
@@ -381,10 +392,6 @@ static int panel_probe(struct platform_device *pdev)
 
         mod->preferred_bpp = panel_mod->info->bpp;
 
-        panel_mod->backlight = of_find_backlight_by_node(node);
-        if (panel_mod->backlight)
-                dev_info(&pdev->dev, "found backlight\n");
-
         return 0;
 
 fail_timings:
@@ -392,6 +399,8 @@ fail_timings:
 
 fail_free:
         tilcdc_module_cleanup(mod);
+        if (panel_mod->backlight)
+                put_device(&panel_mod->backlight->dev);
         return ret;
 }
 
@@ -399,6 +408,10 @@ static int panel_remove(struct platform_device *pdev)
 {
         struct tilcdc_module *mod = dev_get_platdata(&pdev->dev);
         struct panel_module *panel_mod = to_panel_module(mod);
+        struct backlight_device *backlight = panel_mod->backlight;
+
+        if (backlight)
+                put_device(&backlight->dev);
 
         display_timings_release(panel_mod->timings);