[PATCH 2/2] drm/komeda: Initialize encoder possible_clones

[Raveendra Talabattula]

Komeda leaves encoder->possible_clones unset, so it stays at 0 for every
encoder. When userspace asks for writeback, the DRM atomic checks
reject the configuration because no encoder is marked as clone-compatible,
leading to errors such as:

	crtc96 failed valid clone check for mask 0x5

Komeda does not impose per-encoder clone restrictions, so initialize
possible_clones for all registered encoders to the full encoder mask
after encoder creation. This fixes writeback validation.

Signed-off-by: Asad Malik <asad.malik@xxxxxxx>
Signed-off-by: Raveendra Talabattula <raveendra.talabattula@xxxxxxx>
---
 .../gpu/drm/arm/display/komeda/komeda_kms.c   | 20 +++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
index 6ed504099188..0dcc8c05e86b 100644
--- a/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
+++ b/drivers/gpu/drm/arm/display/komeda/komeda_kms.c
@@ -276,7 +276,10 @@ struct komeda_kms_dev *komeda_kms_attach(struct komeda_dev *mdev)
 {
 	struct komeda_kms_dev *kms;
 	struct drm_device *drm;
+	struct drm_encoder *encoder;
 	int err;
+	/* Bitmap of all encoders, assigned to each encoder's possible_clones. */
+	u32 clone_mask = 0;
 
 	kms = devm_drm_dev_alloc(mdev->dev, &komeda_kms_driver,
 				 struct komeda_kms_dev, base);
@@ -311,6 +314,23 @@ struct komeda_kms_dev *komeda_kms_attach(struct komeda_dev *mdev)
 
 	drm_mode_config_reset(drm);
 
+	/*
+	 * Build the full possible_clones mask once. drm_encoder_index()
+	 * returns the bit position assigned to each encoder and BIT() converts
+	 * that index into the corresponding mask value.
+	 *
+	 * Komeda does not have per-encoder clone restrictions, so every encoder
+	 * gets the same mask and is advertised as clone-compatible with all
+	 * other registered encoders.
+	 */
+	drm_for_each_encoder(encoder, drm) {
+		clone_mask |= BIT(drm_encoder_index(encoder));
+	}
+
+	drm_for_each_encoder(encoder, drm) {
+		encoder->possible_clones = clone_mask;
+	}
+
 	err = devm_request_irq(drm->dev, mdev->irq,
 			       komeda_kms_irq_handler, IRQF_SHARED,
 			       drm->driver->name, drm);
-- 
2.43.0