drm: mali-dp: Set encoder possible_clones

Set possible_clones field to report that the writeback connector and
the one driving the display could be enabled at the same time.

Signed-off-by: Alexandru Gheorghe <alexandru-cosmin.gheorghe@arm.com>
Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>

drivers/gpu/drm/arm/malidp_drv.c

@@ -616,6 +616,7 @@ static int malidp_bind(struct device *dev)
 	struct malidp_hw_device *hwdev;
 	struct platform_device *pdev = to_platform_device(dev);
 	struct of_device_id const *dev_id;
+	struct drm_encoder *encoder;
 	/* number of lines for the R, G and B output */
 	u8 output_width[MAX_OUTPUT_CHANNELS];
 	int ret = 0, i;
@@ -737,6 +738,15 @@ static int malidp_bind(struct device *dev)
 		goto bind_fail;
 	}
 
+	/* We expect to have a maximum of two encoders one for the actual
+	 * display and a virtual one for the writeback connector
+	 */
+	WARN_ON(drm->mode_config.num_encoder > 2);
+	list_for_each_entry(encoder, &drm->mode_config.encoder_list, head) {
+		encoder->possible_clones =
+				(1 << drm->mode_config.num_encoder) -  1;
+	}
+
 	ret = malidp_irq_init(pdev);
 	if (ret < 0)
 		goto irq_init_fail;