From 3367c5252524d536afdefbad5fe96290e9ee5ea0 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Tue, 7 Jan 2020 17:59:57 +0100
Subject: drm/sun4i: drc: Make sure we enforce the clock rate
Git-commit: 6fe082b0fbe5a8ce9b16998fc4cb885a9b52f976
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

The DRC needs to run at 300MHz to be functional. This was done so far
using assigned-clocks in the device tree, but that is easy to forget, and
doesn't provide any other guarantee than the rate is going to be roughly
the one requested at probe time.

Therefore it's pretty fragile, so let's just use the exclusive clock API to
enforce it.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200107165957.672435-2-maxime@cerno.tech
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/sun4i/sun6i_drc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun6i_drc.c b/drivers/gpu/drm/sun4i/sun6i_drc.c
index f7ab72244796..4fbe9a6b5182 100644
--- a/drivers/gpu/drm/sun4i/sun6i_drc.c
+++ b/drivers/gpu/drm/sun4i/sun6i_drc.c
@@ -56,6 +56,13 @@ static int sun6i_drc_bind(struct device *dev, struct device *master,
 		ret = PTR_ERR(drc->mod_clk);
 		goto err_disable_bus_clk;
 	}
+
+	ret = clk_set_rate_exclusive(drc->mod_clk, 300000000);
+	if (ret) {
+		dev_err(dev, "Couldn't set the module clock frequency\n");
+		goto err_disable_bus_clk;
+	}
+
 	clk_prepare_enable(drc->mod_clk);
 
 	return 0;
@@ -72,6 +79,7 @@ static void sun6i_drc_unbind(struct device *dev, struct device *master,
 {
 	struct sun6i_drc *drc = dev_get_drvdata(dev);
 
+	clk_rate_exclusive_put(drc->mod_clk);
 	clk_disable_unprepare(drc->mod_clk);
 	clk_disable_unprepare(drc->bus_clk);
 	reset_control_assert(drc->reset);
-- 
2.28.0