drm/dp: Move panel DP AUX backlight support to drm_dp_helper

We were getting a depmod error:
  depmod: ERROR: Cycle detected: drm_kms_helper -> drm -> drm_kms_helper

It looks like the rule is that drm_kms_helper can call into drm, but
drm can't call into drm_kms_helper. That means we've got to move the
DP AUX backlight support into drm_dp_helper.

NOTE: as part of this, I didn't try to do any renames of the main
registration function. Even though it's in the drm_dp_helper, it still
feels very parallel to drm_panel_of_backlight().

Fixes: 10f7b40e4f30 ("drm/panel: add basic DP AUX backlight support")
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reported-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Rajeev Nandan <rajeevny@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210712075933.v2.1.I23eb4cc5a680341e7b3e791632a635566fa5806a@changeid

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 24bbc71..e8eec20 100644 (file)
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -33,9 +33,17 @@
 #include <drm/drm_print.h>
 #include <drm/drm_vblank.h>
 #include <drm/drm_dp_mst_helper.h>
+#include <drm/drm_panel.h>
 
 #include "drm_crtc_helper_internal.h"
 
+struct dp_aux_backlight {
+       struct backlight_device *base;
+       struct drm_dp_aux *aux;
+       struct drm_edp_backlight_info info;
+       bool enabled;
+};
+
 /**
  * DOC: dp helpers
  *
@@ -3462,3 +3470,108 @@ drm_edp_backlight_init(struct drm_dp_aux *aux, struct drm_edp_backlight_info *bl
        return 0;
 }
 EXPORT_SYMBOL(drm_edp_backlight_init);
+
+#if IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
+       (IS_MODULE(CONFIG_DRM_KMS_HELPER) && IS_MODULE(CONFIG_BACKLIGHT_CLASS_DEVICE))
+
+static int dp_aux_backlight_update_status(struct backlight_device *bd)
+{
+       struct dp_aux_backlight *bl = bl_get_data(bd);
+       u16 brightness = backlight_get_brightness(bd);
+       int ret = 0;
+
+       if (!backlight_is_blank(bd)) {
+               if (!bl->enabled) {
+                       drm_edp_backlight_enable(bl->aux, &bl->info, brightness);
+                       bl->enabled = true;
+                       return 0;
+               }
+               ret = drm_edp_backlight_set_level(bl->aux, &bl->info, brightness);
+       } else {
+               if (bl->enabled) {
+                       drm_edp_backlight_disable(bl->aux, &bl->info);
+                       bl->enabled = false;
+               }
+       }
+
+       return ret;
+}
+
+static const struct backlight_ops dp_aux_bl_ops = {
+       .update_status = dp_aux_backlight_update_status,
+};
+
+/**
+ * drm_panel_dp_aux_backlight - create and use DP AUX backlight
+ * @panel: DRM panel
+ * @aux: The DP AUX channel to use
+ *
+ * Use this function to create and handle backlight if your panel
+ * supports backlight control over DP AUX channel using DPCD
+ * registers as per VESA's standard backlight control interface.
+ *
+ * When the panel is enabled backlight will be enabled after a
+ * successful call to &drm_panel_funcs.enable()
+ *
+ * When the panel is disabled backlight will be disabled before the
+ * call to &drm_panel_funcs.disable().
+ *
+ * A typical implementation for a panel driver supporting backlight
+ * control over DP AUX will call this function at probe time.
+ * Backlight will then be handled transparently without requiring
+ * any intervention from the driver.
+ *
+ * drm_panel_dp_aux_backlight() must be called after the call to drm_panel_init().
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux)
+{
+       struct dp_aux_backlight *bl;
+       struct backlight_properties props = { 0 };
+       u16 current_level;
+       u8 current_mode;
+       u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
+       int ret;
+
+       if (!panel || !panel->dev || !aux)
+               return -EINVAL;
+
+       ret = drm_dp_dpcd_read(aux, DP_EDP_DPCD_REV, edp_dpcd,
+                              EDP_DISPLAY_CTL_CAP_SIZE);
+       if (ret < 0)
+               return ret;
+
+       if (!drm_edp_backlight_supported(edp_dpcd)) {
+               DRM_DEV_INFO(panel->dev, "DP AUX backlight is not supported\n");
+               return 0;
+       }
+
+       bl = devm_kzalloc(panel->dev, sizeof(*bl), GFP_KERNEL);
+       if (!bl)
+               return -ENOMEM;
+
+       bl->aux = aux;
+
+       ret = drm_edp_backlight_init(aux, &bl->info, 0, edp_dpcd,
+                                    &current_level, &current_mode);
+       if (ret < 0)
+               return ret;
+
+       props.type = BACKLIGHT_RAW;
+       props.brightness = current_level;
+       props.max_brightness = bl->info.max;
+
+       bl->base = devm_backlight_device_register(panel->dev, "dp_aux_backlight",
+                                                 panel->dev, bl,
+                                                 &dp_aux_bl_ops, &props);
+       if (IS_ERR(bl->base))
+               return PTR_ERR(bl->base);
+
+       panel->backlight = bl->base;
+
+       return 0;
+}
+EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
+
+#endif

diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index 4fa1e3b..f634371 100644 (file)
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -26,20 +26,12 @@
 #include <linux/module.h>
 
 #include <drm/drm_crtc.h>
-#include <drm/drm_dp_helper.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 
 static DEFINE_MUTEX(panel_lock);
 static LIST_HEAD(panel_list);
 
-struct dp_aux_backlight {
-       struct backlight_device *base;
-       struct drm_dp_aux *aux;
-       struct drm_edp_backlight_info info;
-       bool enabled;
-};
-
 /**
  * DOC: drm panel
  *
@@ -350,106 +342,6 @@ int drm_panel_of_backlight(struct drm_panel *panel)
        return 0;
 }
 EXPORT_SYMBOL(drm_panel_of_backlight);
-
-static int dp_aux_backlight_update_status(struct backlight_device *bd)
-{
-       struct dp_aux_backlight *bl = bl_get_data(bd);
-       u16 brightness = backlight_get_brightness(bd);
-       int ret = 0;
-
-       if (!backlight_is_blank(bd)) {
-               if (!bl->enabled) {
-                       drm_edp_backlight_enable(bl->aux, &bl->info, brightness);
-                       bl->enabled = true;
-                       return 0;
-               }
-               ret = drm_edp_backlight_set_level(bl->aux, &bl->info, brightness);
-       } else {
-               if (bl->enabled) {
-                       drm_edp_backlight_disable(bl->aux, &bl->info);
-                       bl->enabled = false;
-               }
-       }
-
-       return ret;
-}
-
-static const struct backlight_ops dp_aux_bl_ops = {
-       .update_status = dp_aux_backlight_update_status,
-};
-
-/**
- * drm_panel_dp_aux_backlight - create and use DP AUX backlight
- * @panel: DRM panel
- * @aux: The DP AUX channel to use
- *
- * Use this function to create and handle backlight if your panel
- * supports backlight control over DP AUX channel using DPCD
- * registers as per VESA's standard backlight control interface.
- *
- * When the panel is enabled backlight will be enabled after a
- * successful call to &drm_panel_funcs.enable()
- *
- * When the panel is disabled backlight will be disabled before the
- * call to &drm_panel_funcs.disable().
- *
- * A typical implementation for a panel driver supporting backlight
- * control over DP AUX will call this function at probe time.
- * Backlight will then be handled transparently without requiring
- * any intervention from the driver.
- *
- * drm_panel_dp_aux_backlight() must be called after the call to drm_panel_init().
- *
- * Return: 0 on success or a negative error code on failure.
- */
-int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux)
-{
-       struct dp_aux_backlight *bl;
-       struct backlight_properties props = { 0 };
-       u16 current_level;
-       u8 current_mode;
-       u8 edp_dpcd[EDP_DISPLAY_CTL_CAP_SIZE];
-       int ret;
-
-       if (!panel || !panel->dev || !aux)
-               return -EINVAL;
-
-       ret = drm_dp_dpcd_read(aux, DP_EDP_DPCD_REV, edp_dpcd,
-                              EDP_DISPLAY_CTL_CAP_SIZE);
-       if (ret < 0)
-               return ret;
-
-       if (!drm_edp_backlight_supported(edp_dpcd)) {
-               DRM_DEV_INFO(panel->dev, "DP AUX backlight is not supported\n");
-               return 0;
-       }
-
-       bl = devm_kzalloc(panel->dev, sizeof(*bl), GFP_KERNEL);
-       if (!bl)
-               return -ENOMEM;
-
-       bl->aux = aux;
-
-       ret = drm_edp_backlight_init(aux, &bl->info, 0, edp_dpcd,
-                                    &current_level, &current_mode);
-       if (ret < 0)
-               return ret;
-
-       props.type = BACKLIGHT_RAW;
-       props.brightness = current_level;
-       props.max_brightness = bl->info.max;
-
-       bl->base = devm_backlight_device_register(panel->dev, "dp_aux_backlight",
-                                                 panel->dev, bl,
-                                                 &dp_aux_bl_ops, &props);
-       if (IS_ERR(bl->base))
-               return PTR_ERR(bl->base);
-
-       panel->backlight = bl->base;
-
-       return 0;
-}
-EXPORT_SYMBOL(drm_panel_dp_aux_backlight);
 #endif
 
 MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");

diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index 729d5d8..a1b2d94 100644 (file)
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -30,6 +30,7 @@
 
 struct drm_device;
 struct drm_dp_aux;
+struct drm_panel;
 
 /*
  * Unless otherwise noted, all values are from the DP 1.1a spec.  Note that
@@ -2200,6 +2201,21 @@ int drm_edp_backlight_enable(struct drm_dp_aux *aux, const struct drm_edp_backli
                             u16 level);
 int drm_edp_backlight_disable(struct drm_dp_aux *aux, const struct drm_edp_backlight_info *bl);
 
+#if IS_ENABLED(CONFIG_DRM_KMS_HELPER) && (IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
+       (IS_MODULE(CONFIG_DRM_KMS_HELPER) && IS_MODULE(CONFIG_BACKLIGHT_CLASS_DEVICE)))
+
+int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux);
+
+#else
+
+static inline int drm_panel_dp_aux_backlight(struct drm_panel *panel,
+                                            struct drm_dp_aux *aux)
+{
+       return 0;
+}
+
+#endif
+
 #ifdef CONFIG_DRM_DP_CEC
 void drm_dp_cec_irq(struct drm_dp_aux *aux);
 void drm_dp_cec_register_connector(struct drm_dp_aux *aux,

diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 71aac75..4602f83 100644 (file)
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -32,7 +32,6 @@ struct backlight_device;
 struct device_node;
 struct drm_connector;
 struct drm_device;
-struct drm_dp_aux;
 struct drm_panel;
 struct display_timing;
 
@@ -209,18 +208,11 @@ static inline int of_drm_get_panel_orientation(const struct device_node *np,
 #if IS_ENABLED(CONFIG_DRM_PANEL) && (IS_BUILTIN(CONFIG_BACKLIGHT_CLASS_DEVICE) || \
        (IS_MODULE(CONFIG_DRM) && IS_MODULE(CONFIG_BACKLIGHT_CLASS_DEVICE)))
 int drm_panel_of_backlight(struct drm_panel *panel);
-int drm_panel_dp_aux_backlight(struct drm_panel *panel, struct drm_dp_aux *aux);
 #else
 static inline int drm_panel_of_backlight(struct drm_panel *panel)
 {
        return 0;
 }
-
-static inline int drm_panel_dp_aux_backlight(struct drm_panel *panel,
-                                            struct drm_dp_aux *aux)
-{
-       return 0;
-}
 #endif
 
 #endif