From: Marek Behún marek.behun@nic.cz
[ Upstream commit 715878016984b2617f6c1f177c50039e12e7bd5b ]
We found out that we are unable to control the PERST# signal via the default pin dedicated to be PERST# pin (GPIO2[3] pin) on A3700 SOC when this pin is in EP_PCIE1_Resetn mode. There is a register in the PCIe register space called PERSTN_GPIO_EN (D0088004[3]), but changing the value of this register does not change the pin output when measuring with voltmeter.
We do not know if this is a bug in the SOC, or if it works only when PCIe controller is in a certain state.
Commit f4c7d053d7f7 ("PCI: aardvark: Wait for endpoint to be ready before training link") says that when this pin changes pinctrl mode from EP_PCIE1_Resetn to GPIO, the PERST# signal is asserted for a brief moment.
So currently the situation is that on A3700 boards the PERST# signal is asserted in U-Boot (because the code in U-Boot issues reset via this pin via GPIO mode), and then in Linux by the obscure and undocumented mechanism described by the above mentioned commit.
We want to issue PERST# signal in a known way, therefore this patch changes the pcie_reset_pin function from "pcie" to "gpio" and adds the reset-gpios property to the PCIe node in device tree files of EspressoBin and Armada 3720 Dev Board (Turris Mox device tree already has this property and uDPU does not have a PCIe port).
Signed-off-by: Marek Behún marek.behun@nic.cz Cc: Remi Pommarel repk@triplefau.lt Tested-by: Tomasz Maciej Nowak tmn505@gmail.com Acked-by: Thomas Petazzoni thomas.petazzoni@bootlin.com Signed-off-by: Gregory CLEMENT gregory.clement@bootlin.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/boot/dts/marvell/armada-3720-db.dts | 3 +++ arch/arm64/boot/dts/marvell/armada-3720-espressobin.dtsi | 1 + arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts | 4 ---- arch/arm64/boot/dts/marvell/armada-37xx.dtsi | 2 +- 4 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/boot/dts/marvell/armada-3720-db.dts b/arch/arm64/boot/dts/marvell/armada-3720-db.dts index f2cc00594d64a..3e5789f372069 100644 --- a/arch/arm64/boot/dts/marvell/armada-3720-db.dts +++ b/arch/arm64/boot/dts/marvell/armada-3720-db.dts @@ -128,6 +128,9 @@
/* CON15(V2.0)/CON17(V1.4) : PCIe / CON15(V2.0)/CON12(V1.4) :mini-PCIe */ &pcie0 { + pinctrl-names = "default"; + pinctrl-0 = <&pcie_reset_pins &pcie_clkreq_pins>; + reset-gpios = <&gpiosb 3 GPIO_ACTIVE_LOW>; status = "okay"; };
diff --git a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dtsi b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dtsi index 42e992f9c8a54..c92ad664cb0ec 100644 --- a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dtsi +++ b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dtsi @@ -47,6 +47,7 @@ phys = <&comphy1 0>; pinctrl-names = "default"; pinctrl-0 = <&pcie_reset_pins &pcie_clkreq_pins>; + reset-gpios = <&gpiosb 3 GPIO_ACTIVE_LOW>; };
/* J6 */ diff --git a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts index 0e0491ca2930d..1452c821f8c09 100644 --- a/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts +++ b/arch/arm64/boot/dts/marvell/armada-3720-turris-mox.dts @@ -128,10 +128,6 @@ }; };
-&pcie_reset_pins { - function = "gpio"; -}; - &pcie0 { pinctrl-names = "default"; pinctrl-0 = <&pcie_reset_pins &pcie_clkreq_pins>; diff --git a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi index 000c135e39b73..7909c146eabf7 100644 --- a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi +++ b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi @@ -317,7 +317,7 @@
pcie_reset_pins: pcie-reset-pins { groups = "pcie1"; - function = "pcie"; + function = "gpio"; };
pcie_clkreq_pins: pcie-clkreq-pins {