linux-kernel - [PATCH 2/3] clk: sunxi-ng: a33: gate then ungate PLL CPU clk after rate change

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Message-Id: <20170413021354.3258-3-wens@csie.org>
Date:   Thu, 13 Apr 2017 10:13:53 +0800
From:   Chen-Yu Tsai <wens@...e.org>
To:     Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...eaurora.org>
Cc:     Chen-Yu Tsai <wens@...e.org>, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-sunxi@...glegroups.com
Subject: [PATCH 2/3] clk: sunxi-ng: a33: gate then ungate PLL CPU clk after rate change

This patch utilizes the new PLL clk notifier to gate then ungate the
PLL CPU clock after rate changes. This should mitigate the system
hangs observed after the introduction of cpufreq for the A33.

Signed-off-by: Chen-Yu Tsai <wens@...e.org>
Tested-by: Quentin Schulz <quentin.schulz@...e-electrons.com>
---
 drivers/clk/sunxi-ng/ccu-sun8i-a33.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/clk/sunxi-ng/ccu-sun8i-a33.c b/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
index 56370c2c7f98..8d38e6510e29 100644
--- a/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
+++ b/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
@@ -756,6 +756,13 @@ static const struct sunxi_ccu_desc sun8i_a33_ccu_desc = {
 	.num_resets	= ARRAY_SIZE(sun8i_a33_ccu_resets),
 };
 
+static struct ccu_pll_nb sun8i_a33_pll_cpu_nb = {
+	.common	= &pll_cpux_clk.common,
+	/* copy from pll_cpux_clk */
+	.enable	= BIT(31),
+	.lock	= BIT(28),
+};
+
 static struct ccu_mux_nb sun8i_a33_cpu_nb = {
 	.common		= &cpux_clk.common,
 	.cm		= &cpux_clk.mux,
@@ -787,6 +794,10 @@ static void __init sun8i_a33_ccu_setup(struct device_node *node)
 
 	sunxi_ccu_probe(node, reg, &sun8i_a33_ccu_desc);
 
+	/* Gate then ungate PLL CPU after any rate changes */
+	ccu_pll_notifier_register(&sun8i_a33_pll_cpu_nb);
+
+	/* Reparent CPU during PLL CPU rate changes */
 	ccu_mux_notifier_register(pll_cpux_clk.common.hw.clk,
 				  &sun8i_a33_cpu_nb);
 }
-- 
2.11.0