linux-kernel - Re: [PATCH] hack to debug acpiphp crash

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Message-ID: <20230725104237.0c8d0dc1@imammedo.users.ipa.redhat.com>
Date:   Tue, 25 Jul 2023 10:42:37 +0200
From:   Igor Mammedov <imammedo@...hat.com>
To:     Woody Suwalski <terraluna977@...il.com>
Cc:     linux-kernel@...r.kernel.org, bhelgaas@...gle.com,
        linux-pci@...r.kernel.org, mst@...hat.com
Subject: Re: [PATCH] hack to debug acpiphp crash

On Tue, 25 Jul 2023 10:06:44 +0200
Igor Mammedov <imammedo@...hat.com> wrote:

> PS:
> What happens is that on resume firmware (likely EC),
> issues ACPI bus check on root ports which (bus check) is
> wired to acpiphp module (though pciehp module was initialized
> at boot to manage root ports), it's likely firmware bug.
> 
> I'd guess the intent behind this was to check if PCIe devices
> were hotplugged while laptop has been asleep, and for
> some reason they didn't use native PCIe hotplug to handle that. 
> However looking at laptop specs you can't hotplug PCIe
> devices via external ports. Given how old laptop is
> it isn't going to be fixed, so we would need a workaround
> or fixup DSDT to skip buscheck.
> 
> The options I see is to keep old kernel as for such case,
> or bail out early from bus check/enable_slot since root port
> is managed by pciehp module (and let it handle hotplug).

scratch all of above out (it's wrong). Looking at DSDT
firmware sends Notify(rpxx, 2 /* Wake */) event. Which
according to spec needs to be handed down to the native
device driver.