Date: Thu, 3 Dec 2015 23:40:13 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Josef Bacik <jbacik@fb.com>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-acpi@vger.kernel.org, bhelgaas@google.com, shli@fb.com,
        kernel-team@fb.com
Subject: Re: [PATCH] pci: completely disable aspm if it's unsupported
Message-ID: <20151203224013.GG14427@amd>
References: <1447856703-2566-1-git-send-email-jbacik@fb.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1447856703-2566-1-git-send-email-jbacik@fb.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1755
Lines: 42

Hi!

> We have some hardware that takes about 30 seconds to setup common clocks for
> ASPM, but our bios'es don't actually allow ASPM.  It seems we had this thing in
> place where we would disable ASPM after the pci bus probe so that we would make
> sure that pre pcie 1.1 devices would be properly skipped during initialization.
> This is because the mechanism to disable ASPM doesn't actually disable the
> setting up of the link state stuff, it just keeps us from changing the link
> state after the fact.  So instead make it so that when we call pcie_no_aspm()
> that we disable ASPM completley, that is we skip setting up the link state and
> everything.  This way we avoid the costly setup for a feature we cannot support
> in the first place and we also make sure we are safe from future tampering with
> the ASPM link state.  Thanks,

On thinkpad x60, I have similar problem.

I'm carying this for long long time now:

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index a32ba75..5eb7621 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -700,7 +700,7 @@ static int __init acpi_pci_init(void)
 
 	if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_ASPM) {
 		pr_info("ACPI FADT declares the system doesn't support PCIe ASPM, so disable it\n");
-		pcie_no_aspm();
+//		pcie_no_aspm();
 	}
 
 	ret = register_acpi_bus_type(&acpi_pci_bus);


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/