From c0c8fa36fd012996ce1cf32bf2c465120d699c0c Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Tue, 7 Jan 2020 17:59:56 +0100
Subject: drm/sun4i: backend: Make sure we enforce the clock rate
Git-commit: 451debe55715acafdcacba6a879e6ccb8eca23ce
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 backend 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/20200107165957.672435-1-maxime@cerno.tech
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/gpu/drm/sun4i/sun4i_backend.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/sun4i/sun4i_backend.c b/drivers/gpu/drm/sun4i/sun4i_backend.c
index 4e29f4fe4a05..072ea113e6be 100644
--- a/drivers/gpu/drm/sun4i/sun4i_backend.c
+++ b/drivers/gpu/drm/sun4i/sun4i_backend.c
@@ -856,6 +856,13 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
ret = PTR_ERR(backend->mod_clk);
goto err_disable_bus_clk;
}
+
+ ret = clk_set_rate_exclusive(backend->mod_clk, 300000000);
+ if (ret) {
+ dev_err(dev, "Couldn't set the module clock frequency\n");
+ goto err_disable_bus_clk;
+ }
+
clk_prepare_enable(backend->mod_clk);
backend->ram_clk = devm_clk_get(dev, "ram");
@@ -932,6 +939,7 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
err_disable_ram_clk:
clk_disable_unprepare(backend->ram_clk);
err_disable_mod_clk:
+ clk_rate_exclusive_put(backend->mod_clk);
clk_disable_unprepare(backend->mod_clk);
err_disable_bus_clk:
clk_disable_unprepare(backend->bus_clk);
@@ -952,6 +960,7 @@ static void sun4i_backend_unbind(struct device *dev, struct device *master,
sun4i_backend_free_sat(dev);
clk_disable_unprepare(backend->ram_clk);
+ clk_rate_exclusive_put(backend->mod_clk);
clk_disable_unprepare(backend->mod_clk);
clk_disable_unprepare(backend->bus_clk);
reset_control_assert(backend->reset);
--
2.28.0