[PATCH] drm: atmel_hlcdc: Add support for get_timings

[davidcdueck@googlemail.com (David Dueck)]

drm_panel supports querying timing ranges. If the supplied mode does
not work with the hlcdc we query the panel and try to find a suitable
mode.

Signed-off-by: David Dueck <davidcdueck@googlemail.com>
---
 drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c | 118 +++++++++++++++++++----
 1 file changed, 98 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
index 9c45130..ea36c24 100644
--- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
+++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_output.c
@@ -20,6 +20,7 @@
  */
 
 #include <linux/of_graph.h>
+#include <video/display_timing.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_panel.h>
@@ -78,6 +79,8 @@ drm_encoder_to_atmel_hlcdc_rgb_output(struct drm_encoder *encoder)
 struct atmel_hlcdc_panel {
 	struct atmel_hlcdc_rgb_output base;
 	struct drm_panel *panel;
+	struct display_timing *timings;
+	unsigned int num_timings;
 };
 
 static inline struct atmel_hlcdc_panel *
@@ -104,14 +107,6 @@ static void atmel_hlcdc_panel_encoder_disable(struct drm_encoder *encoder)
 	drm_panel_disable(panel->panel);
 }
 
-static bool
-atmel_hlcdc_panel_encoder_mode_fixup(struct drm_encoder *encoder,
-				     const struct drm_display_mode *mode,
-				     struct drm_display_mode *adjusted)
-{
-	return true;
-}
-
 static void
 atmel_hlcdc_rgb_encoder_mode_set(struct drm_encoder *encoder,
 				 struct drm_display_mode *mode,
@@ -142,8 +137,86 @@ atmel_hlcdc_rgb_encoder_mode_set(struct drm_encoder *encoder,
 			   cfg);
 }
 
+/**
+ * atmel_hlcdc_choose_parameter - choose timing parameter
+ * @dc_min: minimum parameter value allowed by dc
+ * @dc_max: maximum parameter value allowed by dc
+ * @te: parameter range allowed by panel
+ * @result: chosen parameter
+ *
+ * DESCRIPTION:
+ * If there is overlap in the allowed ranges, we will pick a parameter
+ * minimizing the distance to te.typ. If not, we return te.min or te.max.
+ **/
+static u32 atmel_hlcdc_choose_parameter(u32 dc_min, u32 dc_max,
+					struct timing_entry te)
+{
+	if (te.typ <= dc_max && te.typ >= dc_min)
+		return te.typ;
+	else if (te.typ > dc_max)
+		return max(dc_max, te.min);
+	else
+		return min(dc_min, te.max);
+}
+
+static void atmel_hlcdc_calculate_mode(struct display_timing *timings,
+				       struct drm_display_mode *adjusted_mode)
+{
+	u32 hsync_len, hfront_porch, hback_porch;
+	u32 vsync_len, vfront_porch, vback_porch;
+
+	hsync_len = atmel_hlcdc_choose_parameter(1, 0x40, timings->hsync_len);
+	vsync_len = atmel_hlcdc_choose_parameter(1, 0x40, timings->vsync_len);
+
+	hfront_porch = atmel_hlcdc_choose_parameter(1, 0x200,
+						    timings->hfront_porch);
+	hback_porch = atmel_hlcdc_choose_parameter(1, 0x200,
+						   timings->hback_porch);
+	vfront_porch = atmel_hlcdc_choose_parameter(1, 0x40,
+						    timings->vfront_porch);
+	vback_porch = atmel_hlcdc_choose_parameter(0, 0x40,
+						   timings->vback_porch);
+
+	adjusted_mode->hsync_start = adjusted_mode->hdisplay + hfront_porch;
+	adjusted_mode->hsync_end = adjusted_mode->hsync_start + hsync_len;
+	adjusted_mode->htotal = adjusted_mode->hsync_end + hback_porch;
+
+	adjusted_mode->vsync_start = adjusted_mode->vdisplay + vfront_porch;
+	adjusted_mode->vsync_end = adjusted_mode->vsync_start + vsync_len;
+	adjusted_mode->vtotal = adjusted_mode->vsync_end + vback_porch;
+}
+
+static int
+atmel_hlcdc_panel_encoder_atomic_check(struct drm_encoder *encoder,
+				       struct drm_crtc_state *crtc_state,
+				       struct drm_connector_state *conn_state)
+{
+	struct atmel_hlcdc_rgb_output *rgb =
+			drm_encoder_to_atmel_hlcdc_rgb_output(encoder);
+	struct atmel_hlcdc_panel *panel = atmel_hlcdc_rgb_output_to_panel(rgb);
+	struct drm_display_mode *mode = &crtc_state->mode;
+	struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode;
+	int i;
+
+	if (atmel_hlcdc_dc_mode_valid(rgb->dc, mode) == MODE_OK)
+		return 0;
+
+	for (i = 0; i < panel->num_timings; i++) {
+		if (panel->timings->hactive.typ != mode->hdisplay ||
+		    panel->timings->vactive.typ != mode->vdisplay)
+			continue;
+
+		atmel_hlcdc_calculate_mode(panel->timings, adjusted_mode);
+		if (atmel_hlcdc_dc_mode_valid(rgb->dc, adjusted_mode) ==
+		    MODE_OK)
+			return 0;
+	}
+
+	return -EINVAL;
+}
+
 static struct drm_encoder_helper_funcs atmel_hlcdc_panel_encoder_helper_funcs = {
-	.mode_fixup = atmel_hlcdc_panel_encoder_mode_fixup,
+	.atomic_check = atmel_hlcdc_panel_encoder_atomic_check,
 	.mode_set = atmel_hlcdc_rgb_encoder_mode_set,
 	.disable = atmel_hlcdc_panel_encoder_disable,
 	.enable = atmel_hlcdc_panel_encoder_enable,
@@ -168,16 +241,6 @@ static int atmel_hlcdc_panel_get_modes(struct drm_connector *connector)
 	return panel->panel->funcs->get_modes(panel->panel);
 }
 
-static int atmel_hlcdc_rgb_mode_valid(struct drm_connector *connector,
-				      struct drm_display_mode *mode)
-{
-	struct atmel_hlcdc_rgb_output *rgb =
-			drm_connector_to_atmel_hlcdc_rgb_output(connector);
-
-	return atmel_hlcdc_dc_mode_valid(rgb->dc, mode);
-}
-
-
 
 static struct drm_encoder *
 atmel_hlcdc_rgb_best_encoder(struct drm_connector *connector)
@@ -190,7 +253,6 @@ atmel_hlcdc_rgb_best_encoder(struct drm_connector *connector)
 
 static struct drm_connector_helper_funcs atmel_hlcdc_panel_connector_helper_funcs = {
 	.get_modes = atmel_hlcdc_panel_get_modes,
-	.mode_valid = atmel_hlcdc_rgb_mode_valid,
 	.best_encoder = atmel_hlcdc_rgb_best_encoder,
 };
 
@@ -273,6 +335,22 @@ static int atmel_hlcdc_create_panel_output(struct drm_device *dev,
 	drm_panel_attach(p, &panel->base.connector);
 	panel->panel = p;
 
+	if (!panel->panel->funcs->get_timings)
+		return 0;
+
+	panel->num_timings =
+		panel->panel->funcs->get_timings(panel->panel, 0, NULL);
+	panel->timings =
+		devm_kzalloc(dev->dev,
+			     panel->num_timings * sizeof(struct display_timing),
+			     GFP_KERNEL);
+
+	if (!panel->timings)
+		return 0;
+
+	panel->panel->funcs->get_timings(panel->panel, panel->num_timings,
+					 panel->timings);
+
 	return 0;
 
 err_encoder_cleanup:
-- 
2.3.6