arm64: dts: marvell: armada-37xx: Set pcie_reset_pin to gpio function

commit 715878016984b2617f6c1f177c50039e12e7bd5b upstream.

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: Marek Behún <kabel@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/boot/dts/marvell/armada-3720-db.dts b/arch/arm64/boot/dts/marvell/armada-3720-db.dts
index 9df0f06ce6070a4c17c724d52bb956504dc8e2b7..0a0e9e19e879e37af03cc8c1dd7b0f6b92e26256 100644 (file)
--- a/arch/arm64/boot/dts/marvell/armada-3720-db.dts
+++ b/arch/arm64/boot/dts/marvell/armada-3720-db.dts
@@ -155,6 +155,9 @@
 
 /* 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.dts b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts
index 13c0ec053ada91b53c5ca81d6482555dd4e80420..89c7385390f40b27170e67e1048c1121f15a9888 100644 (file)
--- a/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts
+++ b/arch/arm64/boot/dts/marvell/armada-3720-espressobin.dts
@@ -82,6 +82,9 @@
 
 /* J9 */
 &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-37xx.dtsi b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
index a4c81a1c77b7bfad45933cfd4dc93ecc9b35257a..b369356e74195b2b94c11164e0ede5aa3e52a746 100644 (file)
--- a/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
+++ b/arch/arm64/boot/dts/marvell/armada-37xx.dtsi
@@ -241,7 +241,7 @@
 
                                pcie_reset_pins: pcie-reset-pins {
                                        groups = "pcie1";
-                                       function = "pcie";
+                                       function = "gpio";
                                };
 
                                pcie_clkreq_pins: pcie-clkreq-pins {