[PATCH 0/4] arm64: amlogic: t7: describe the VIM4 supplies and keep the fabric clocks running

[PATCH 0/4] arm64: amlogic: t7: describe the VIM4 supplies and keep the fabric clocks running

[Lucas Tanure]

The Khadas VIM4 has needed clk_ignore_unused to boot reliably. Without it
the board hangs at random, loses storage and corrupts memory, and the
failures move around from boot to boot.

Six of the SoC's PWM outputs drive the board's voltage regulators: the
always-on domain, both CPU clusters, the GPU, the NPU and the DRAM. None
of them were described, so Linux saw the outputs as unused and switched
them off about a second into boot. The regulators then drifted away from
the levels the bootloader had set, which is where the corruption and the
random hangs came from. 
Thanks to Chuan Liu from Amlogic for helping me indetify which clocks are
critical.

Separately, four clocks feed the bus that carries data between the
peripherals and memory. Nothing claims those either, and switching them
off leaves any device that starts a transfer afterwards stuck. The SD
card comes up about two seconds into boot, so it was the visible victim.

Two of the patches are pin group fixes. The description named groups that
do not exist in the pinctrl driver, so anything referencing them refused
to probe. That is what the supplies patch needs in order to work, and it
had a second effect worth mentioning: the failing probe left one device
unbound, which kept the clock controller's sync_state() deferred forever
and quietly stopped every peripheral clock from ever being switched off.
The board looked healthy for entirely the wrong reason.

Tested on a VIM4 booting from SD with no clk_ignore_unused: 74 clocks are
still switched off, but the card enumerates and the root filesystem mounts
and memtest runs clean over 512 MiB.

Thread about these issues in Vim4:

https://lore.kernel.org/linux-clk/3930906f-783b-4d72-9260-ba25cc8081cb@linux.com/

Lucas Tanure (4):
  clk: meson: t7: keep the memory fabric clocks running
  arm64: dts: amlogic: t7: fix the pin groups of two PWM outputs
  arm64: dts: amlogic: t7: khadas-vim4: add the PWM-driven supplies
  arm64: dts: amlogic: t7: fix the pin groups of the vsync PWM

 .../amlogic/amlogic-t7-a311d2-khadas-vim4.dts | 110 +++++++++++++++++-
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi   |  44 ++++++-
 drivers/clk/meson/t7-peripherals.c            |  13 ++-
 3 files changed, 156 insertions(+), 11 deletions(-)

-- 
2.55.0

[PATCH 1/4] clk: meson: t7: keep the memory fabric clocks running

[Lucas Tanure]

Four clocks feed the bus that moves data between the peripherals and
memory. Nothing in Linux claims them, so they were switched off shortly
after boot, and any device that started a transfer after that point
simply stopped. The SD card, which comes up about two seconds in, never
finished reading its identification.

There is no device these clocks belong to, so mark them as always
needed.

Fixes: fab4d651b592 ("clk: meson: t7: add t7 clock peripherals controller driver")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Lucas Tanure <tanure@linux.com>
---
 drivers/clk/meson/t7-peripherals.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/meson/t7-peripherals.c b/drivers/clk/meson/t7-peripherals.c
index 214db7850d86..55d09e78593b 100644
--- a/drivers/clk/meson/t7-peripherals.c
+++ b/drivers/clk/meson/t7-peripherals.c
@@ -945,11 +945,16 @@ static T7_SYS_PCLK(sys_aucpu,		SYS_CLK_EN0_REG0, 14,	0);
 static T7_SYS_PCLK(sys_cec,		SYS_CLK_EN0_REG0, 16,	0);
 static T7_SYS_PCLK(sys_gdc,		SYS_CLK_EN0_REG0, 17,	0);
 static T7_SYS_PCLK(sys_deswarp,		SYS_CLK_EN0_REG0, 18,	0);
-static T7_SYS_PCLK(sys_ampipe_nand,	SYS_CLK_EN0_REG0, 19,	0);
+/*
+ * NOTE: sys_ampipe_nand and sys_am2axi0..2 provide the clock to the AXI bus
+ * used for DMA between the peripherals and the DRAM. After the clocks are
+ * disabled, a device that starts a transfer cannot complete it.
+ */
+static T7_SYS_PCLK(sys_ampipe_nand,	SYS_CLK_EN0_REG0, 19,	CLK_IS_CRITICAL);
 static T7_SYS_PCLK(sys_ampipe_eth,	SYS_CLK_EN0_REG0, 20,	0);
-static T7_SYS_PCLK(sys_am2axi0,		SYS_CLK_EN0_REG0, 21,	0);
-static T7_SYS_PCLK(sys_am2axi1,		SYS_CLK_EN0_REG0, 22,	0);
-static T7_SYS_PCLK(sys_am2axi2,		SYS_CLK_EN0_REG0, 23,	0);
+static T7_SYS_PCLK(sys_am2axi0,		SYS_CLK_EN0_REG0, 21,	CLK_IS_CRITICAL);
+static T7_SYS_PCLK(sys_am2axi1,		SYS_CLK_EN0_REG0, 22,	CLK_IS_CRITICAL);
+static T7_SYS_PCLK(sys_am2axi2,		SYS_CLK_EN0_REG0, 23,	CLK_IS_CRITICAL);
 static T7_SYS_PCLK(sys_sd_emmc_a,	SYS_CLK_EN0_REG0, 24,	0);
 static T7_SYS_PCLK(sys_sd_emmc_b,	SYS_CLK_EN0_REG0, 25,	0);
 static T7_SYS_PCLK(sys_sd_emmc_c,	SYS_CLK_EN0_REG0, 26,	0);
-- 
2.55.0

[PATCH 2/4] arm64: dts: amlogic: t7: fix the pin groups of two PWM outputs

[Lucas Tanure]

Two of the PWM outputs can each appear on more than one pin, but the
description named a single group that does not exist, so anything using
it refused to start.

Name the real groups instead, one entry per pin, the same way the other
multi-pin PWM output is already described.

Fixes: 2a2a7b9701a7 ("arm64: dts: amlogic: t7: Add PWM pinctrl nodes")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Lucas Tanure <tanure@linux.com>
---
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi | 32 ++++++++++++++++++---
 1 file changed, 28 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
index c3dc479b137d..8c4bd683cce0 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
@@ -458,9 +458,25 @@ mux {
 					};
 				};
 
-				pwm_ao_g_pins: pwm-ao-g {
+				pwm_ao_g_d11_pins: pwm-ao-g-d11 {
 					mux {
-						groups = "pwm_ao_g";
+						groups = "pwm_ao_g_d11";
+						function = "pwm_ao_g";
+						bias-disable;
+					};
+				};
+
+				pwm_ao_g_d7_pins: pwm-ao-g-d7 {
+					mux {
+						groups = "pwm_ao_g_d7";
+						function = "pwm_ao_g";
+						bias-disable;
+					};
+				};
+
+				pwm_ao_g_e_pins: pwm-ao-g-e {
+					mux {
+						groups = "pwm_ao_g_e";
 						function = "pwm_ao_g";
 						bias-disable;
 					};
@@ -474,9 +490,17 @@ mux {
 					};
 				};
 
-				pwm_ao_h_pins: pwm-ao-h {
+				pwm_ao_h_d5_pins: pwm-ao-h-d5 {
+					mux {
+						groups = "pwm_ao_h_d5";
+						function = "pwm_ao_h";
+						bias-disable;
+					};
+				};
+
+				pwm_ao_h_d10_pins: pwm-ao-h-d10 {
 					mux {
-						groups = "pwm_ao_h";
+						groups = "pwm_ao_h_d10";
 						function = "pwm_ao_h";
 						bias-disable;
 					};
-- 
2.55.0

[PATCH 3/4] arm64: dts: amlogic: t7: khadas-vim4: add the PWM-driven supplies

[Lucas Tanure]

The board powers its two CPU clusters, the GPU, the NPU, the memory and
the always-on domain from regulators steered by PWM outputs. None of
them were described, so Linux treated those outputs as unused and
switched them off part way through boot. The supplies then drifted away
from the levels the bootloader had set, which showed up as random hangs
and memory corruption.

Describe each supply so it has an owner and is left alone.

The voltage ranges are read off the feedback networks on the board
schematic. VDDNPU is deliberately not the range in Amlogic's own
device tree: this board fits a different feedback resistor, which
puts it about 40mV higher at both ends.

Fixes: 8c45bf9ae4ef ("arm64: dts: amlogic: t7: khadas-vim4: Add power regulators")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Lucas Tanure <tanure@linux.com>
---
 .../amlogic/amlogic-t7-a311d2-khadas-vim4.dts | 110 +++++++++++++++++-
 1 file changed, 109 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts b/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts
index c94afaaf8826..77abfd555ec5 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts
@@ -104,6 +104,66 @@ vcc5v0_usb: regulator-vcc-usb {
 		enable-active-high;
 	};
 
+	vdd_ddr: regulator-vddddr {
+		/*
+		 * SY8003ADFC Regulator.
+		 */
+		compatible = "pwm-regulator";
+		regulator-name = "VDDDDR";
+		regulator-min-microvolt = <690000>;
+		regulator-max-microvolt = <890000>;
+		pwm-supply = <&dc_in>;
+		pwms = <&pwm_ao_gh 0 1500 0>;
+		pwm-dutycycle-range = <100 0>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
+	vdd_ee: regulator-vddee {
+		/*
+		 * MP8756GD Regulator.
+		 */
+		compatible = "pwm-regulator";
+		regulator-name = "VDDEE";
+		regulator-min-microvolt = <700000>;
+		regulator-max-microvolt = <922000>;
+		pwm-supply = <&dc_in>;
+		pwms = <&pwm_ao_ab 0 1500 0>;
+		pwm-dutycycle-range = <100 0>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
+	vdd_gpu: regulator-vddgpu {
+		/*
+		 * SY8003ADFC Regulator.
+		 */
+		compatible = "pwm-regulator";
+		regulator-name = "VDDGPU";
+		regulator-min-microvolt = <700000>;
+		regulator-max-microvolt = <922000>;
+		pwm-supply = <&dc_in>;
+		pwms = <&pwm_ao_ef 0 1500 0>;
+		pwm-dutycycle-range = <100 0>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
+	vdd_npu: regulator-vddnpu {
+		/*
+		 * SY8003ADFC Regulator.
+		 */
+		compatible = "pwm-regulator";
+		regulator-name = "VDDNPU";
+		regulator-min-microvolt = <733000>;
+		regulator-max-microvolt = <933000>;
+		pwm-supply = <&dc_in>;
+		pwms = <&pwm_ao_ef 1 1500 0>;
+		pwm-dutycycle-range = <100 0>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
 	vddao_1v8: regulator-vddao-1v8 {
 		compatible = "regulator-fixed";
 		regulator-name = "VDDAO_1V8";
@@ -122,6 +182,36 @@ vddao_3v3: regulator-vddao-3v3 {
 		regulator-always-on;
 	};
 
+	vddcpu_a: regulator-vddcpu-a {
+		/*
+		 * MP8756GD Regulator.
+		 */
+		compatible = "pwm-regulator";
+		regulator-name = "VDDCPU_A";
+		regulator-min-microvolt = <689000>;
+		regulator-max-microvolt = <1049000>;
+		pwm-supply = <&dc_in>;
+		pwms = <&pwm_ao_cd 1 1500 0>;
+		pwm-dutycycle-range = <100 0>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
+	vddcpu_b: regulator-vddcpu-b {
+		/*
+		 * MP8756GD Regulator.
+		 */
+		compatible = "pwm-regulator";
+		regulator-name = "VDDCPU_B";
+		regulator-min-microvolt = <689000>;
+		regulator-max-microvolt = <1049000>;
+		pwm-supply = <&dc_in>;
+		pwms = <&pwm_ao_ab 1 1500 0>;
+		pwm-dutycycle-range = <100 0>;
+		regulator-boot-on;
+		regulator-always-on;
+	};
+
 	vddio_1v8: regulator-vddio-1v8 {
 		compatible = "regulator-fixed";
 		regulator-name = "VDDIO_1V8";
@@ -172,9 +262,27 @@ &pwm_ab {
 	pinctrl-names = "default";
 };
 
+&pwm_ao_ab {
+	status = "okay";
+	pinctrl-0 = <&pwm_ao_a_pins>, <&pwm_ao_b_pins>;
+	pinctrl-names = "default";
+};
+
 &pwm_ao_cd {
 	status = "okay";
-	pinctrl-0 = <&pwm_ao_c_d_pins>;
+	pinctrl-0 = <&pwm_ao_c_d_pins>, <&pwm_ao_d_pins>;
+	pinctrl-names = "default";
+};
+
+&pwm_ao_ef {
+	status = "okay";
+	pinctrl-0 = <&pwm_ao_e_pins>, <&pwm_ao_f_pins>;
+	pinctrl-names = "default";
+};
+
+&pwm_ao_gh {
+	status = "okay";
+	pinctrl-0 = <&pwm_ao_g_e_pins>;
 	pinctrl-names = "default";
 };
 
-- 
2.55.0

[PATCH 4/4] arm64: dts: amlogic: t7: fix the pin groups of the vsync PWM

[Lucas Tanure]

The vsync PWM output can appear on either of two pins, but the
description named a single group that does not exist, so anything using
it would refuse to start.

Name the real groups instead, one entry per pin. No board describes this
output yet, so nothing changes today.

Fixes: 2a2a7b9701a7 ("arm64: dts: amlogic: t7: Add PWM pinctrl nodes")
Assisted-by: Claude:claude-opus-5
Signed-off-by: Lucas Tanure <tanure@linux.com>
---
 arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
index 8c4bd683cce0..719e111bc3dd 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7.dtsi
@@ -546,9 +546,17 @@ mux {
 					};
 				};
 
-				pwm_vs_pins: pwm-vs {
+				pwm_vs_y_pins: pwm-vs-y {
 					mux {
-						groups = "pwm_vs";
+						groups = "pwm_vs_y";
+						function = "pwm_vs";
+						bias-disable;
+					};
+				};
+
+				pwm_vs_h_pins: pwm-vs-h {
+					mux {
+						groups = "pwm_vs_h";
 						function = "pwm_vs";
 						bias-disable;
 					};
-- 
2.55.0