[PATCH 4/4] drm/ast: astdp: Validate display modes

[Thomas Zimmermann]

Validate each display mode against the astdp transmitter chips. Filters
out modes that the chip does not support.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/gpu/drm/ast/ast_dp.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/ast/ast_dp.c b/drivers/gpu/drm/ast/ast_dp.c
index 056991afde7f..19c04687b0fe 100644
--- a/drivers/gpu/drm/ast/ast_dp.c
+++ b/drivers/gpu/drm/ast/ast_dp.c
@@ -300,6 +300,19 @@ static const struct drm_encoder_funcs ast_astdp_encoder_funcs = {
 	.destroy = drm_encoder_cleanup,
 };
 
+static enum drm_mode_status
+ast_astdp_encoder_helper_mode_valid(struct drm_encoder *encoder,
+				    const struct drm_display_mode *mode)
+{
+	int res;
+
+	res = ast_astdp_get_mode_index(mode->hdisplay, mode->vdisplay);
+	if (res < 0)
+		return MODE_NOMODE;
+
+	return MODE_OK;
+}
+
 static void ast_astdp_encoder_helper_atomic_mode_set(struct drm_encoder *encoder,
 						     struct drm_crtc_state *crtc_state,
 						     struct drm_connector_state *conn_state)
@@ -389,6 +402,7 @@ static int ast_astdp_encoder_helper_atomic_check(struct drm_encoder *encoder,
 }
 
 static const struct drm_encoder_helper_funcs ast_astdp_encoder_helper_funcs = {
+	.mode_valid = ast_astdp_encoder_helper_mode_valid,
 	.atomic_mode_set = ast_astdp_encoder_helper_atomic_mode_set,
 	.atomic_enable = ast_astdp_encoder_helper_atomic_enable,
 	.atomic_disable = ast_astdp_encoder_helper_atomic_disable,
-- 
2.48.1