From aa01338c018469274848a973bcbd287ef341937c Mon Sep 17 00:00:00 2001
From: Tobias Regnery <tobias.regnery@gmail.com>
Date: Mon, 27 Mar 2017 11:57:53 +0200
Subject: [PATCH 1/4] clk: sunxi-ng: fix build error without
CONFIG_RESET_CONTROLLER
With CONFIG_RESET_CONTROLLER=n we get the following link error in the
sunxi-ng clk driver:
drivers/built-in.o: In function `sunxi_ccu_probe':
mux-core.c:(.text+0x12fe68): undefined reference to 'reset_controller_register'
mux-core.c:(.text+0x12fe68): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol 'reset_controller_register'
Fix this by adding the appropriate select statement.
Signed-off-by: Tobias Regnery <tobias.regnery@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
drivers/clk/sunxi-ng/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/clk/sunxi-ng/Kconfig b/drivers/clk/sunxi-ng/Kconfig
index 72109d2cf41b2..e8eca1fc31e98 100644
--- a/drivers/clk/sunxi-ng/Kconfig
+++ b/drivers/clk/sunxi-ng/Kconfig
@@ -1,6 +1,7 @@
config SUNXI_CCU
bool "Clock support for Allwinner SoCs"
depends on ARCH_SUNXI || COMPILE_TEST
+ select RESET_CONTROLLER
default ARCH_SUNXI
if SUNXI_CCU
From e87741ac6c578b240409a8114b9350a58b0f9e93 Mon Sep 17 00:00:00 2001
From: Tobias Regnery <tobias.regnery@gmail.com>
Date: Mon, 10 Apr 2017 14:15:44 +0200
Subject: [PATCH 2/4] clk: sunxi-ng: fix build failure in ccu-sun9i-a80 driver
The ccu-sun9i-a80 driver uses the ccu_mult_ops struct, but unlike the other
users it doesen't select the corresponding Kconfig symbol under which the
struct is compiled in.
This results in the following link error with CONFIG_SUN9I_A80_CCU=y and
CONFIG_SUNXI_CCU_MULT=n:
drivers/built-in.o:(.data+0x2d638): undefined reference to 'ccu_mult_ops'
Fix this by explicitly selecting CONFIG_SUNXI_CCU_MULT like the other
users of the struct.
Signed-off-by: Tobias Regnery <tobias.regnery@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
drivers/clk/sunxi-ng/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/clk/sunxi-ng/Kconfig b/drivers/clk/sunxi-ng/Kconfig
index e8eca1fc31e98..1c23573010176 100644
--- a/drivers/clk/sunxi-ng/Kconfig
+++ b/drivers/clk/sunxi-ng/Kconfig
@@ -136,6 +136,7 @@ config SUN8I_V3S_CCU
config SUN9I_A80_CCU
bool "Support for the Allwinner A80 CCU"
select SUNXI_CCU_DIV
+ select SUNXI_CCU_MULT
select SUNXI_CCU_GATE
select SUNXI_CCU_NKMP
select SUNXI_CCU_NM
From 02ae2bc6febd90cf3de61b6a1bdf491966ed410f Mon Sep 17 00:00:00 2001
From: Chen-Yu Tsai <wens@csie.org>
Date: Thu, 13 Apr 2017 10:13:52 +0800
Subject: [PATCH 3/4] clk: sunxi-ng: Add clk notifier to gate then ungate PLL
clocks
In common PLL designs, changes to the dividers take effect almost
immediately, while changes to the multipliers (implemented as
dividers in the feedback loop) take a few cycles to work into
the feedback loop for the PLL to stablize.
Sometimes when the PLL clock rate is changed, the decrease in the
divider is too much for the decrease in the multiplier to catch up.
The PLL clock rate will spike, and in some cases, might lock up
completely. This is especially the case if the divider changed is
the pre-divider, which affects the reference frequency.
This patch introduces a clk notifier callback that will gate and
then ungate a clk after a rate change, effectively resetting it,
so it continues to work, despite any possible lockups. Care must
be taken to reparent any consumers to other temporary clocks during
the rate change, and that this notifier callback must be the first
to be registered.
This is intended to fix occasional lockups with cpufreq on newer
Allwinner SoCs, such as the A33 and the H3. Previously it was
thought that reparenting the cpu clock away from the PLL while
it stabilized was enough, as this worked quite well on the A31.
On the A33, hangs have been observed after cpufreq was recently
introduced. With the H3, a more thorough test [1] showed that
reparenting alone isn't enough. The system still locks up unless
the dividers are limited to 1.
A hunch was if the PLL was stuck in some unknown state, perhaps
gating then ungating it would bring it back to normal. Tests
done by Icenowy Zheng using Ondrej's test firmware shows this
to be a valid solution.
[1] http://www.spinics.net/lists/arm-kernel/msg552501.html
Reported-by: Ondrej Jirman <megous@megous.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Tested-by: Icenowy Zheng <icenowy@aosc.io>
Tested-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
---
drivers/clk/sunxi-ng/ccu_common.c | 49 +++++++++++++++++++++++++++++++
drivers/clk/sunxi-ng/ccu_common.h | 12 ++++++++
2 files changed, 61 insertions(+)
diff --git a/drivers/clk/sunxi-ng/ccu_common.c b/drivers/clk/sunxi-ng/ccu_common.c
index 8a47bafd78905..9d8724715a435 100644
--- a/drivers/clk/sunxi-ng/ccu_common.c
+++ b/drivers/clk/sunxi-ng/ccu_common.c
@@ -14,11 +14,13 @@
* GNU General Public License for more details.
*/
+#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/iopoll.h>
#include <linux/slab.h>
#include "ccu_common.h"
+#include "ccu_gate.h"
#include "ccu_reset.h"
static DEFINE_SPINLOCK(ccu_lock);
@@ -39,6 +41,53 @@ void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
}
+/*
+ * This clock notifier is called when the frequency of a PLL clock is
+ * changed. In common PLL designs, changes to the dividers take effect
+ * almost immediately, while changes to the multipliers (implemented
+ * as dividers in the feedback loop) take a few cycles to work into
+ * the feedback loop for the PLL to stablize.
+ *
+ * Sometimes when the PLL clock rate is changed, the decrease in the
+ * divider is too much for the decrease in the multiplier to catch up.
+ * The PLL clock rate will spike, and in some cases, might lock up
+ * completely.
+ *
+ * This notifier callback will gate and then ungate the clock,
+ * effectively resetting it, so it proceeds to work. Care must be
+ * taken to reparent consumers to other temporary clocks during the
+ * rate change, and that this notifier callback must be the first
+ * to be registered.
+ */
+static int ccu_pll_notifier_cb(struct notifier_block *nb,
+ unsigned long event, void *data)
+{
+ struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
+ int ret = 0;
+
+ if (event != POST_RATE_CHANGE)
+ goto out;
+
+ ccu_gate_helper_disable(pll->common, pll->enable);
+
+ ret = ccu_gate_helper_enable(pll->common, pll->enable);
+ if (ret)
+ goto out;
+
+ ccu_helper_wait_for_lock(pll->common, pll->lock);
+
+out:
+ return notifier_from_errno(ret);
+}
+
+int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
+{
+ pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
+
+ return clk_notifier_register(pll_nb->common->hw.clk,
+ &pll_nb->clk_nb);
+}
+
int sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
const struct sunxi_ccu_desc *desc)
{
diff --git a/drivers/clk/sunxi-ng/ccu_common.h b/drivers/clk/sunxi-ng/ccu_common.h
index 73d81dc58fc5a..d6fdd7a789aa7 100644
--- a/drivers/clk/sunxi-ng/ccu_common.h
+++ b/drivers/clk/sunxi-ng/ccu_common.h
@@ -83,6 +83,18 @@ struct sunxi_ccu_desc {
void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock);
+struct ccu_pll_nb {
+ struct notifier_block clk_nb;
+ struct ccu_common *common;
+
+ u32 enable;
+ u32 lock;
+};
+
+#define to_ccu_pll_nb(_nb) container_of(_nb, struct ccu_pll_nb, clk_nb)
+
+int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb);
+
int sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
const struct sunxi_ccu_desc *desc);
From 372fa10172a2f9e1bfbc70778449628e82b72341 Mon Sep 17 00:00:00 2001
From: Chen-Yu Tsai <wens@csie.org>
Date: Thu, 13 Apr 2017 10:13:53 +0800
Subject: [PATCH 4/4] 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@csie.org>
Tested-by: Quentin Schulz <quentin.schulz@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-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 a7b3c08ed0e23..2c69b631967ae 100644
--- a/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
+++ b/drivers/clk/sunxi-ng/ccu-sun8i-a33.c
@@ -752,6 +752,13 @@ 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,
@@ -783,6 +790,10 @@ 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);
}