drm: Include the encoder itself in possible_clones

The docs say possible_clones should always include the encoder itself.
Since most drivers don't want to deal with the complexities of cloning
let's allow them to set possible_clones=0 and instead we'll fix that
up in the core.

We can't put this special case into drm_encoder_init() because drivers
will have to fill up possible_clones after adding all the relevant
encoders. Otherwise they wouldn't know the proper encoder indexes to
use. So we'll just do it just before registering the device.

v2: Don't set the bit if possible_clones!=0 so that the
    validation (coming soon) will WARN (Thomas)
    Fix up the docs to allow possible_clones==0 (Daniel)
    .late_register() is too late, introduce drm_mode_config_validate()
    which gets called _before_ we register the char device (Daniel)

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200211162208.16224-2-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/drm_crtc_internal.h b/drivers/gpu/drm/drm_crtc_internal.h
index feba683c12a6e1998ed2b7c5ee9d47bacd66542c..d2d43e0b060ba55aed5cf7321e90e4d20ee78363 100644 (file)
--- a/drivers/gpu/drm/drm_crtc_internal.h
+++ b/drivers/gpu/drm/drm_crtc_internal.h
@@ -82,6 +82,7 @@ int drm_mode_setcrtc(struct drm_device *dev,
 /* drm_mode_config.c */
 int drm_modeset_register_all(struct drm_device *dev);
 void drm_modeset_unregister_all(struct drm_device *dev);
+void drm_mode_config_validate(struct drm_device *dev);
 
 /* drm_modes.c */
 const char *drm_get_mode_status_name(enum drm_mode_status status);

diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 7b1a628d1f6e3277657a5582c1f196fa1a7fe851..65a0acb79323ca6ad88b5aebabf0033696349764 100644 (file)
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -946,6 +946,9 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
        struct drm_driver *driver = dev->driver;
        int ret;
 
+       if (!driver->load)
+               drm_mode_config_validate(dev);
+
        if (drm_dev_needs_global_mutex(dev))
                mutex_lock(&drm_global_mutex);
 

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 08e6eff6a1797b2e0686af7610f061b587ca419d..75e357c7e84da3a42ed4bd801e962873385d74f1 100644 (file)
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -532,3 +532,22 @@ void drm_mode_config_cleanup(struct drm_device *dev)
        drm_modeset_lock_fini(&dev->mode_config.connection_mutex);
 }
 EXPORT_SYMBOL(drm_mode_config_cleanup);
+
+/*
+ * For some reason we want the encoder itself included in
+ * possible_clones. Make life easy for drivers by allowing them
+ * to leave possible_clones unset if no cloning is possible.
+ */
+static void fixup_encoder_possible_clones(struct drm_encoder *encoder)
+{
+       if (encoder->possible_clones == 0)
+               encoder->possible_clones = drm_encoder_mask(encoder);
+}
+
+void drm_mode_config_validate(struct drm_device *dev)
+{
+       struct drm_encoder *encoder;
+
+       drm_for_each_encoder(encoder, dev)
+               fixup_encoder_possible_clones(encoder);
+}

diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
index 4370e039c015a7501a073297c0e51e75761b278a..34b7213bfab63edb42d1b8bd1ed4fce063aaff43 100644 (file)
--- a/include/drm/drm_encoder.h
+++ b/include/drm/drm_encoder.h
@@ -159,7 +159,9 @@ struct drm_encoder {
         * encoders can be used in a cloned configuration, they both should have
         * each another bits set.
         *
-        * In reality almost every driver gets this wrong.
+        * As an exception to the above rule if the driver doesn't implement
+        * any cloning it can leave @possible_clones set to 0. The core will
+        * automagically fix this up by setting the bit for the encoder itself.
         *
         * Note that since encoder objects can't be hotplugged the assigned indices
         * are stable and hence known before registering all objects.