linux-kernel - [PATCH 5.4 29/68] PCI/PM: Avoid putting Elo i2 PCIe Ports in D3cold

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Date:   Mon, 23 May 2022 19:04:56 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Stefan Gottwald <gottwald@...l.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH 5.4 29/68] PCI/PM: Avoid putting Elo i2 PCIe Ports in D3cold

From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

commit 92597f97a40bf661bebceb92e26ff87c76d562d4 upstream.

If a Root Port on Elo i2 is put into D3cold and then back into D0, the
downstream device becomes permanently inaccessible, so add a bridge D3 DMI
quirk for that system.

This was exposed by 14858dcc3b35 ("PCI: Use pci_update_current_state() in
pci_enable_device_flags()"), but before that commit the Root Port in
question had never been put into D3cold for real due to a mismatch between
its power state retrieved from the PCI_PM_CTRL register (which was
accessible even though the platform firmware indicated that the port was in
D3cold) and the state of an ACPI power resource involved in its power
management.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215715
Link: https://lore.kernel.org/r/11980172.O9o76ZdvQC@kreacher
Reported-by: Stefan Gottwald <gottwald@...l.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: stable@...r.kernel.org	# v5.15+
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/pci/pci.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2613,6 +2613,16 @@ static const struct dmi_system_id bridge
 			DMI_MATCH(DMI_BOARD_VENDOR, "Gigabyte Technology Co., Ltd."),
 			DMI_MATCH(DMI_BOARD_NAME, "X299 DESIGNARE EX-CF"),
 		},
+		/*
+		 * Downstream device is not accessible after putting a root port
+		 * into D3cold and back into D0 on Elo i2.
+		 */
+		.ident = "Elo i2",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Elo Touch Solutions"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Elo i2"),
+			DMI_MATCH(DMI_PRODUCT_VERSION, "RevB"),
+		},
 	},
 #endif
 	{ }