[PATCH 1/4] drm/simple_kms_helper: enable use of external encoder

[Linus Walleij <linus.walleij@linaro.org>]

This makes it possible to pass a connector with an already
attached external encoder into the simple KMS helper.

This is helpful for my MCDE drivers, as it is pretty simple
but uses DSI to communicate with the displays and bridges.
DSI requires the use of the DSI bus which in turn requires
us to set up a custom connector from the display driver.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpu/drm/drm_simple_kms_helper.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index 917812448d1b..e7499b939235 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -266,7 +266,7 @@ int drm_simple_display_pipe_init(struct drm_device *dev,
 			const uint64_t *format_modifiers,
 			struct drm_connector *connector)
 {
-	struct drm_encoder *encoder = &pipe->encoder;
+	struct drm_encoder *encoder;
 	struct drm_plane *plane = &pipe->plane;
 	struct drm_crtc *crtc = &pipe->crtc;
 	int ret;
@@ -289,10 +289,23 @@ int drm_simple_display_pipe_init(struct drm_device *dev,
 	if (ret)
 		return ret;
 
-	encoder->possible_crtcs = drm_crtc_mask(crtc);
-	ret = drm_encoder_init(dev, encoder, &drm_simple_kms_encoder_funcs,
-			       DRM_MODE_ENCODER_NONE, NULL);
-	if (ret || !connector)
+	/* Other encoder already attached to the connector */
+	if (connector->encoder_ids[0] != 0) {
+		encoder = drm_encoder_find(connector->dev, NULL,
+					   connector->encoder_ids[0]);
+		encoder->possible_crtcs = drm_crtc_mask(crtc);
+		DRM_INFO("an encoder is already attached to the connector\n");
+	} else {
+		encoder = &pipe->encoder;
+		encoder->possible_crtcs = drm_crtc_mask(crtc);
+		ret = drm_encoder_init(dev, encoder,
+				       &drm_simple_kms_encoder_funcs,
+				       DRM_MODE_ENCODER_NONE, NULL);
+		if (ret)
+			return ret;
+	}
+
+	if (!connector)
 		return ret;
 
 	return drm_connector_attach_encoder(connector, encoder);
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel