From: Marc Zyngier <maz@kernel.org>
To: linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org
Cc: kernel-team@android.com, Alyssa Rosenzweig <alyssa@rosenzweig.io>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Bjorn Helgaas <bhelgaas@google.com>
Subject: [PATCH] PCI: apple: Reset the port for 100ms on probe
Date: Wed, 17 Nov 2021 16:00:53 +0000 [thread overview]
Message-ID: <20211117160053.232158-1-maz@kernel.org> (raw)
While the Apple PCIe driver works correctly when directly booted
from the firmware, it fails to initialise when the kernel is booted
from a bootloader using PCIe such as u-boot.
That's beacuse we're missing a proper reset of the port (we only
clear the reset, but never assert it).
Bring the port back to life by wiggling the #PERST pin for 100ms
(as per the spec).
Fixes: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/controller/pcie-apple.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index 1bf4d75b61be..bbea5f6e0a68 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -543,6 +543,9 @@ static int apple_pcie_setup_port(struct apple_pcie *pcie,
if (ret < 0)
return ret;
+ /* Hold #PERST for 100ms as per the spec */
+ gpiod_set_value(reset, 0);
+ msleep(100);
rmw_set(PORT_PERST_OFF, port->base + PORT_PERST);
gpiod_set_value(reset, 1);
--
2.30.2
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next reply other threads:[~2021-11-17 16:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-17 16:00 Marc Zyngier [this message]
2021-11-17 20:12 ` [PATCH] PCI: apple: Reset the port for 100ms on probe Bjorn Helgaas
2021-11-17 20:28 ` Pali Rohár
2021-11-18 10:01 ` Marc Zyngier
2021-11-18 10:31 ` Pali Rohár
2021-11-18 12:57 ` Marc Zyngier
2021-11-20 11:32 ` Pali Rohár
2021-11-18 10:45 ` Marc Zyngier
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