From: Chen-Yu Tsai <wens@csie.org>
Date: Tue, 10 Oct 2017 11:20:02 +0800
Subject: drm/sun4i: hdmi: Allow using second PLL as TMDS clk parent
Git-commit: cc67ae90be461ff78ed0b92681213e988138312a
Patch-mainline: v4.15-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

On SoCs with two display pipelines, it is possible that the two
pipelines are active at the same time, with potentially incompatible
dot clocks.

Let the HDMI encoder's TMDS clock go through all of its parents when
calculating possible clock rates. This allows usage of the second video
PLL as its parent.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010032008.682-6-wens@csie.org

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c |   53 +++++++++++++++-------------
 1 file changed, 29 insertions(+), 24 deletions(-)

--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -67,11 +67,11 @@ static unsigned long sun4i_tmds_calc_div
 static int sun4i_tmds_determine_rate(struct clk_hw *hw,
 				     struct clk_rate_request *req)
 {
-	struct clk_hw *parent;
+	struct clk_hw *parent = NULL;
 	unsigned long best_parent = 0;
 	unsigned long rate = req->rate;
 	int best_div = 1, best_half = 1;
-	int i, j;
+	int i, j, p;
 
 	/*
 	 * We only consider PLL3, since the TCON is very likely to be
@@ -79,32 +79,37 @@ static int sun4i_tmds_determine_rate(str
 	 * clock, so we should not need to do anything.
 	 */
 
-	parent = clk_hw_get_parent_by_index(hw, 0);
-	if (!parent)
-		return -EINVAL;
-
-	for (i = 1; i < 3; i++) {
-		for (j = 1; j < 16; j++) {
-			unsigned long ideal = rate * i * j;
-			unsigned long rounded;
-
-			rounded = clk_hw_round_rate(parent, ideal);
-
-			if (rounded == ideal) {
-				best_parent = rounded;
-				best_half = i;
-				best_div = j;
-				goto out;
-			}
-
-			if (abs(rate - rounded / i) <
-			    abs(rate - best_parent / best_div)) {
-				best_parent = rounded;
-				best_div = i;
+	for (p = 0; p < clk_hw_get_num_parents(hw); p++) {
+		parent = clk_hw_get_parent_by_index(hw, p);
+		if (!parent)
+			continue;
+
+		for (i = 1; i < 3; i++) {
+			for (j = 1; j < 16; j++) {
+				unsigned long ideal = rate * i * j;
+				unsigned long rounded;
+
+				rounded = clk_hw_round_rate(parent, ideal);
+
+				if (rounded == ideal) {
+					best_parent = rounded;
+					best_half = i;
+					best_div = j;
+					goto out;
+				}
+
+				if (abs(rate - rounded / i) <
+				    abs(rate - best_parent / best_div)) {
+					best_parent = rounded;
+					best_div = i;
+				}
 			}
 		}
 	}
 
+	if (!parent)
+		return -EINVAL;
+
 out:
 	req->rate = best_parent / best_half / best_div;
 	req->best_parent_rate = best_parent;