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* [PATCH AUTOSEL 4.19 21/97] clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table
       [not found] <20190108192949.122407-1-sashal@kernel.org>
@ 2019-01-08 19:28 ` Sasha Levin
  2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 34/97] clk: imx: make mux parent strings const Sasha Levin
  2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 50/97] clk: imx6q: reset exclusive gates on init Sasha Levin
  2 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2019-01-08 19:28 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: Martin Blumenstingl, Neil Armstrong, Sasha Levin, linux-amlogic,
	linux-clk

From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

[ Upstream commit ad9b2b8e53af61375322e3c7d624acf3a3ef53b0 ]

The public S805 datasheet only mentions that
HHI_SYS_CPU_CLK_CNTL1[20:29] contains a divider called "cpu_scale_div".
Unfortunately it does not mention how to use the register contents.

The Amlogic 3.10 GPL kernel sources are using the following code to
calculate the CPU clock based on that register (taken from
arch/arm/mach-meson8/clock.c in the 3.10 Amlogic kernel, shortened to
make it easier to read):
N = (aml_read_reg32(P_HHI_SYS_CPU_CLK_CNTL1) >> 20) & 0x3FF;
if (sel == 3) /* use cpu_scale_div */
  div = 2 * N;
else
  div = ... /* not relevant for this example */
cpu_clk = parent_clk / div;

This suggests that the formula is: parent_rate / 2 * register_value
However, running perf (which can measure the CPU clock rate thanks to
the ARM PMU) shows that this formula is not correct.
This can be reproduced with the following steps:
1. boot into u-boot
2. let the CPU clock run off the XTAL clock:
   mw.l 0xC110419C 0x30 1
3. set the cpu_scale_div register:
   to value 0x1: mw.l 0xC110415C 0x801016A2 1
   to value 0x2: mw.l 0xC110415C 0x802016A2 1
   to value 0x5: mw.l 0xC110415C 0x805016A2 1
4. let the CPU clock run off cpu_scale_div:
   mw.l 0xC110419C 0xbd 1
5. boot Linux
6. run: perf stat -aB stress --cpu 4 --timeout 10
7. check the "cycles" value

I get the following results depending on the cpu_scale_div value:
- (cpu_in_sel - this is the input clock for cpu_scale_div - runs at
   1.2GHz)
- 0x1 = 300MHz
- 0x2 = 200MHz
- 0x5 = 100MHz

This means that the actual formula to calculate the output of the
cpu_scale_div clock is: parent_rate / 2 * (register value + 1).

The register value 0x0 is reserved. When letting the CPU clock run off
the cpu_scale_div while the value is 0x0 the whole board hangs (even in
u-boot).

I also verified this with the TWD timer: when adding this to the .dts
without specifying it's clock it will auto-detect the PERIPH (which is
the input clock of the TWD) clock rate (and the result is shown in the
kernel log). On Meson8, Meson8b and Meson8m2 the PERIPH clock is CPUCLK
divided by 4. This also matched for all three test-cases from above (in
all cases the TWD timer clock rate was approx. one fourth of the CPU
clock rate).

A small note regarding the "fixes" tag: the original issue seems to
exist virtually since forever. Even commit 28b9fcd016126e ("clk:
meson8b: Add support for Meson8b clocks") seems to handle this wrong. I
still decided to use commit 251b6fd38bcb9c ("clk: meson: rework meson8b
cpu clock") because this is the first commit which gets the CPU hiearchy
correct and thus it's the first commit where the cpu_scale_div register
is used correctly (apart from the bug in the cpu_scale_table).

Fixes: 251b6fd38bcb9c ("clk: meson: rework meson8b cpu clock")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lkml.kernel.org/r/20180927085921.24627-2-martin.blumenstingl@googlemail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/clk/meson/meson8b.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/meson/meson8b.c b/drivers/clk/meson/meson8b.c
index 74697e145dde..50060e895e7a 100644
--- a/drivers/clk/meson/meson8b.c
+++ b/drivers/clk/meson/meson8b.c
@@ -568,13 +568,14 @@ static struct clk_fixed_factor meson8b_cpu_div3 = {
 };
 
 static const struct clk_div_table cpu_scale_table[] = {
-	{ .val = 2, .div = 4 },
-	{ .val = 3, .div = 6 },
-	{ .val = 4, .div = 8 },
-	{ .val = 5, .div = 10 },
-	{ .val = 6, .div = 12 },
-	{ .val = 7, .div = 14 },
-	{ .val = 8, .div = 16 },
+	{ .val = 1, .div = 4 },
+	{ .val = 2, .div = 6 },
+	{ .val = 3, .div = 8 },
+	{ .val = 4, .div = 10 },
+	{ .val = 5, .div = 12 },
+	{ .val = 6, .div = 14 },
+	{ .val = 7, .div = 16 },
+	{ .val = 8, .div = 18 },
 	{ /* sentinel */ },
 };
 
-- 
2.19.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* [PATCH AUTOSEL 4.19 34/97] clk: imx: make mux parent strings const
       [not found] <20190108192949.122407-1-sashal@kernel.org>
  2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 21/97] clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table Sasha Levin
@ 2019-01-08 19:28 ` Sasha Levin
  2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 50/97] clk: imx6q: reset exclusive gates on init Sasha Levin
  2 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2019-01-08 19:28 UTC (permalink / raw)
  To: linux-kernel, stable
  Cc: A.s. Dong, Stephen Boyd, Michael Turquette, Shawn Guo,
	Stephen Boyd, Sasha Levin, linux-clk

From: "A.s. Dong" <aisheng.dong@nxp.com>

[ Upstream commit 9e5ef7a57ca75a1b9411c46caeeb6881124284a3 ]

As the commit 2893c379461a ("clk: make strings in parent name arrays
const"), let's make the parent strings const, otherwise we may meet
the following warning when compiling:

drivers/clk/imx/clk-imx7ulp.c: In function 'imx7ulp_clocks_init':
drivers/clk/imx/clk-imx7ulp.c:73:35: warning: passing argument 5 of
	'imx_clk_mux_flags' discards 'const' qualifier from pointer target type

  clks[IMX7ULP_CLK_APLL_PRE_SEL] = imx_clk_mux_flags("apll_pre_sel", base + 0x508, 0,
	1, pll_pre_sels, ARRAY_SIZE(pll_pre_sels), CLK_SET_PARENT_GATE);
                                   ^
In file included from drivers/clk/imx/clk-imx7ulp.c:23:0:
drivers/clk/imx/clk.h:200:27: note: expected 'const char **' but argument is
 of type 'const char * const*'
...

Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/clk/imx/clk-busy.c      |  2 +-
 drivers/clk/imx/clk-fixup-mux.c |  2 +-
 drivers/clk/imx/clk.h           | 18 +++++++++++-------
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/imx/clk-busy.c b/drivers/clk/imx/clk-busy.c
index 99036527eb0d..e695622c5aa5 100644
--- a/drivers/clk/imx/clk-busy.c
+++ b/drivers/clk/imx/clk-busy.c
@@ -154,7 +154,7 @@ static const struct clk_ops clk_busy_mux_ops = {
 
 struct clk *imx_clk_busy_mux(const char *name, void __iomem *reg, u8 shift,
 			     u8 width, void __iomem *busy_reg, u8 busy_shift,
-			     const char **parent_names, int num_parents)
+			     const char * const *parent_names, int num_parents)
 {
 	struct clk_busy_mux *busy;
 	struct clk *clk;
diff --git a/drivers/clk/imx/clk-fixup-mux.c b/drivers/clk/imx/clk-fixup-mux.c
index c9b327e0a8dd..44817c1b0b88 100644
--- a/drivers/clk/imx/clk-fixup-mux.c
+++ b/drivers/clk/imx/clk-fixup-mux.c
@@ -70,7 +70,7 @@ static const struct clk_ops clk_fixup_mux_ops = {
 };
 
 struct clk *imx_clk_fixup_mux(const char *name, void __iomem *reg,
-			      u8 shift, u8 width, const char **parents,
+			      u8 shift, u8 width, const char * const *parents,
 			      int num_parents, void (*fixup)(u32 *val))
 {
 	struct clk_fixup_mux *fixup_mux;
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 8076ec040f37..e65c1115d978 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -63,14 +63,14 @@ struct clk *imx_clk_busy_divider(const char *name, const char *parent_name,
 
 struct clk *imx_clk_busy_mux(const char *name, void __iomem *reg, u8 shift,
 			     u8 width, void __iomem *busy_reg, u8 busy_shift,
-			     const char **parent_names, int num_parents);
+			     const char * const *parent_names, int num_parents);
 
 struct clk *imx_clk_fixup_divider(const char *name, const char *parent,
 				  void __iomem *reg, u8 shift, u8 width,
 				  void (*fixup)(u32 *val));
 
 struct clk *imx_clk_fixup_mux(const char *name, void __iomem *reg,
-			      u8 shift, u8 width, const char **parents,
+			      u8 shift, u8 width, const char * const *parents,
 			      int num_parents, void (*fixup)(u32 *val));
 
 static inline struct clk *imx_clk_fixed(const char *name, int rate)
@@ -79,7 +79,8 @@ static inline struct clk *imx_clk_fixed(const char *name, int rate)
 }
 
 static inline struct clk *imx_clk_mux_ldb(const char *name, void __iomem *reg,
-		u8 shift, u8 width, const char **parents, int num_parents)
+			u8 shift, u8 width, const char * const *parents,
+			int num_parents)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			CLK_SET_RATE_NO_REPARENT | CLK_SET_RATE_PARENT, reg,
@@ -192,7 +193,8 @@ static inline struct clk *imx_clk_gate4(const char *name, const char *parent,
 }
 
 static inline struct clk *imx_clk_mux(const char *name, void __iomem *reg,
-		u8 shift, u8 width, const char **parents, int num_parents)
+			u8 shift, u8 width, const char * const *parents,
+			int num_parents)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			CLK_SET_RATE_NO_REPARENT, reg, shift,
@@ -200,7 +202,8 @@ static inline struct clk *imx_clk_mux(const char *name, void __iomem *reg,
 }
 
 static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
-		u8 shift, u8 width, const char **parents, int num_parents)
+			u8 shift, u8 width, const char * const *parents,
+			int num_parents)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE,
@@ -208,8 +211,9 @@ static inline struct clk *imx_clk_mux2(const char *name, void __iomem *reg,
 }
 
 static inline struct clk *imx_clk_mux_flags(const char *name,
-		void __iomem *reg, u8 shift, u8 width, const char **parents,
-		int num_parents, unsigned long flags)
+			void __iomem *reg, u8 shift, u8 width,
+			const char * const *parents, int num_parents,
+			unsigned long flags)
 {
 	return clk_register_mux(NULL, name, parents, num_parents,
 			flags | CLK_SET_RATE_NO_REPARENT, reg, shift, width, 0,
-- 
2.19.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* [PATCH AUTOSEL 4.19 50/97] clk: imx6q: reset exclusive gates on init
       [not found] <20190108192949.122407-1-sashal@kernel.org>
  2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 21/97] clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table Sasha Levin
  2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 34/97] clk: imx: make mux parent strings const Sasha Levin
@ 2019-01-08 19:28 ` Sasha Levin
  2 siblings, 0 replies; 3+ messages in thread
From: Sasha Levin @ 2019-01-08 19:28 UTC (permalink / raw)
  To: linux-kernel, stable; +Cc: Lucas Stach, Stephen Boyd, Sasha Levin, linux-clk

From: Lucas Stach <l.stach@pengutronix.de>

[ Upstream commit f7542d817733f461258fd3a47d77da35b2d9fc81 ]

The exclusive gates may be set up in the wrong way by software running
before the clock driver comes up. In that case the exclusive setup is
locked in its initial state, as the complementary function can't be
activated without disabling the initial setup first.

To avoid this lock situation, reset the exclusive gates to the off
state and allow the kernel to provide the proper setup.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Dong Aisheng <Aisheng.dong@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/clk/imx/clk-imx6q.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/imx/clk-imx6q.c b/drivers/clk/imx/clk-imx6q.c
index 8c7c2fcb8d94..c509324f6338 100644
--- a/drivers/clk/imx/clk-imx6q.c
+++ b/drivers/clk/imx/clk-imx6q.c
@@ -508,8 +508,12 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	 * lvds1_gate and lvds2_gate are pseudo-gates.  Both can be
 	 * independently configured as clock inputs or outputs.  We treat
 	 * the "output_enable" bit as a gate, even though it's really just
-	 * enabling clock output.
+	 * enabling clock output. Initially the gate bits are cleared, as
+	 * otherwise the exclusive configuration gets locked in the setup done
+	 * by software running before the clock driver, with no way to change
+	 * it.
 	 */
+	writel(readl(base + 0x160) & ~0x3c00, base + 0x160);
 	clk[IMX6QDL_CLK_LVDS1_GATE] = imx_clk_gate_exclusive("lvds1_gate", "lvds1_sel", base + 0x160, 10, BIT(12));
 	clk[IMX6QDL_CLK_LVDS2_GATE] = imx_clk_gate_exclusive("lvds2_gate", "lvds2_sel", base + 0x160, 11, BIT(13));
 
-- 
2.19.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

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     [not found] <20190108192949.122407-1-sashal@kernel.org>
2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 21/97] clk: meson: meson8b: fix incorrect divider mapping in cpu_scale_table Sasha Levin
2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 34/97] clk: imx: make mux parent strings const Sasha Levin
2019-01-08 19:28 ` [PATCH AUTOSEL 4.19 50/97] clk: imx6q: reset exclusive gates on init Sasha Levin

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