linux-kernel - Re: [PATCH] PCI: PM: Quirk bridge D3 on Elo i2

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Date:   Thu, 26 May 2022 17:12:58 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PCI <linux-pci@...r.kernel.org>,
        Stefan Gottwald <gottwald@...l.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PCI: PM: Quirk bridge D3 on Elo i2

On Thu, Mar 31, 2022 at 07:38:51PM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> If one of the PCIe root ports 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 commit 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
> Reported-by: Stefan Gottwald <gottwald@...l.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/pci/pci.c |   10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> Index: linux-pm/drivers/pci/pci.c
> ===================================================================
> --- linux-pm.orig/drivers/pci/pci.c
> +++ linux-pm/drivers/pci/pci.c
> @@ -2920,6 +2920,16 @@ 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"),
> +		},
>  	},

This has already made it to Linus' and some stable trees, but I think
we need the following touchup.  I plan to send it right after my v5.19
pull request.

commit a99f6bb133df ("PCI/PM: Fix bridge_d3_blacklist[] Elo i2 overwrite of Gigabyte X299")
Author: Bjorn Helgaas <bhelgaas@...gle.com>
Date:   Thu May 26 16:52:23 2022 -0500

    PCI/PM: Fix bridge_d3_blacklist[] Elo i2 overwrite of Gigabyte X299
    
    92597f97a40b ("PCI/PM: Avoid putting Elo i2 PCIe Ports in D3cold") omitted
    braces around the new Elo i2 entry, so it overwrote the existing Gigabyte
    X299 entry.
    
    Found by:
    
      $ make W=1 drivers/pci/pci.o
        CC      drivers/pci/pci.o
      drivers/pci/pci.c:2974:12: error: initialized field overwritten [-Werror=override-init]
       2974 |   .ident = "Elo i2",
            |            ^~~~~~~~
    
    Fixes: 92597f97a40b ("PCI/PM: Avoid putting Elo i2 PCIe Ports in D3cold")
    Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
    Cc: stable@...r.kernel.org  # v5.15+

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index d25122fbe98a..5b400a742621 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2920,6 +2920,8 @@ static const struct dmi_system_id bridge_d3_blacklist[] = {
 			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.