[PATCH v3 7/7] drm: Allow drivers to leave encoder->possible_crtcs==0

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Let's simplify life of driver by allowing them to leave
encoder->possible_crtcs unset if they have no restrictions
in crtc<->encoder linkage. We'll just populate possible_crtcs
with the full crtc mask when registering the encoder so that
userspace doesn't have to deal with drivers not populating
this correctly.

Cc: Thomas Zimmermann <tzimmermann at suse.de>
Cc: Daniel Vetter <daniel at ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
We might not actually need/want this, but included it here for
future reference if that assumption turns out to be wrong.
---
 drivers/gpu/drm/drm_mode_config.c | 15 ++++++++++++++-
 include/drm/drm_encoder.h         |  4 ++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c
index 4c1b350ddb95..ce18c3dd0bde 100644
--- a/drivers/gpu/drm/drm_mode_config.c
+++ b/drivers/gpu/drm/drm_mode_config.c
@@ -592,6 +592,17 @@ static u32 full_crtc_mask(struct drm_device *dev)
 	return crtc_mask;
 }
 
+/*
+ * Make life easy for drivers by allowing them to leave
+ * possible_crtcs unset if there are not crtc<->encoder
+ * restrictions.
+ */
+static void fixup_encoder_possible_crtcs(struct drm_encoder *encoder)
+{
+	if (encoder->possible_crtcs == 0)
+		encoder->possible_crtcs = full_crtc_mask(encoder->dev);
+}
+
 static void validate_encoder_possible_crtcs(struct drm_encoder *encoder)
 {
 	u32 crtc_mask = full_crtc_mask(encoder->dev);
@@ -608,8 +619,10 @@ void drm_mode_config_validate(struct drm_device *dev)
 {
 	struct drm_encoder *encoder;
 
-	drm_for_each_encoder(encoder, dev)
+	drm_for_each_encoder(encoder, dev) {
 		fixup_encoder_possible_clones(encoder);
+		fixup_encoder_possible_crtcs(encoder);
+	}
 
 	drm_for_each_encoder(encoder, dev) {
 		validate_encoder_possible_clones(encoder);
diff --git a/include/drm/drm_encoder.h b/include/drm/drm_encoder.h
index b236269f41ac..bd033c5618bf 100644
--- a/include/drm/drm_encoder.h
+++ b/include/drm/drm_encoder.h
@@ -142,6 +142,10 @@ struct drm_encoder {
 	 * the bits for all &drm_crtc objects this encoder can be connected to
 	 * before calling drm_dev_register().
 	 *
+	 * As an exception to the above rule if any crtc can be connected to
+	 * the encoder the driver can leave @possible_crtcs set to 0. The core
+	 * will automagically fix this up by setting the bit for every crtc.
+	 *
 	 * You will get a WARN if you get this wrong in the driver.
 	 *
 	 * Note that since CRTC objects can't be hotplugged the assigned indices
-- 
2.24.1