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7158780169
linux/arch/arm64
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Marek Behún 7158780169 arm64: dts: marvell: armada-37xx: Set pcie_reset_pin to gpio function 
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 f4c7d053d7 ("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>
2020-05-17 17:51:43 +02:00
..
boot arm64: dts: marvell: armada-37xx: Set pcie_reset_pin to gpio function 2020-05-17 17:51:43 +02:00
configs ARM: defconfig updates 2020-04-03 15:15:10 -07:00
crypto SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
include mm/vma: define a default value for VM_DATA_DEFAULT_FLAGS 2020-04-10 15:36:21 -07:00
kernel arm64 fixes: 2020-04-09 11:04:16 -07:00
kvm virtio: fixes, vdpa 2020-04-08 10:51:53 -07:00
lib arm64: fix spelling mistake "ca not" -> "cannot" 2020-03-17 18:22:40 +00:00
mm mm/memory_hotplug: add pgprot_t to mhp_params 2020-04-10 15:36:21 -07:00
net
xen
Kbuild
Kconfig arm64 fixes: 2020-04-09 11:04:16 -07:00
Kconfig.debug arm64: remove CONFIG_DEBUG_ALIGN_RODATA feature 2020-04-01 21:44:43 +01:00
Kconfig.platforms ARM: SoC updates 2020-04-03 15:02:35 -07:00
Makefile arm64: Always force a branch protection mode when the compiler has one 2020-04-01 21:23:40 +01:00