linux-kernel - Re: [ath5k-devel] [PATCH v3] ath5k: disable ASPM

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Date:	Mon, 26 Jul 2010 15:43:04 -0700
From:	"Luis R. Rodriguez" <mcgrof@...il.com>
To:	Matthew Garrett <mjg59@...f.ucam.org>
Cc:	Maxim Levitsky <maximlevitsky@...il.com>,
	"ath5k-devel@...ts.ath5k.org" <ath5k-devel@...ts.ath5k.org>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
	David Quan <David.Quan@...eros.com>,
	"Luis R. Rodriguez" <mcgrof@...badil.infradead.org>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	"kernel-team@...ts.ubuntu.com" <kernel-team@...ts.ubuntu.com>,
	Luis Rodriguez <Luis.Rodriguez@...eros.com>,
	Jussi Kivilinna <jussi.kivilinna@...et.fi>,
	"tim.gardner@...onical.com" <tim.gardner@...onical.com>
Subject: Re: [ath5k-devel] [PATCH v3] ath5k: disable ASPM

On Mon, Jul 26, 2010 at 3:33 PM, Matthew Garrett <mjg59@...f.ucam.org> wrote:
> On Mon, Jul 26, 2010 at 03:31:28PM -0700, Luis R. Rodriguez wrote:
>> On Mon, Jul 26, 2010 at 3:29 PM, Matthew Garrett <mjg59@...f.ucam.org> wrote:
>> > On Mon, Jul 26, 2010 at 03:26:37PM -0700, Luis R. Rodriguez wrote:
>> >
>> >> What I meant was that the PCI config space would already have L1
>> >> enabled if L1 worked, so I don't see why we would need to nitpick out
>> >> specifics here. All Atheros PCIE chips should work with L1. The advise
>> >> given is to disable L0s though. I believe AR2425 would be one which
>> >> likely had L0s enabled but requires it to be disabled. Not sure of
>> >> others. But this is why I am saying this can be done globally for all
>> >> ath5k chipsets.
>> >
>> > If L1 is set but the chip is pre-PCIe 1.1 then we'll disable L1 unless
>> > the driver tells us that it's functional. The .inf from the Windows
>> > driver seemed to suggest that only a subset of the chips re-enabled L1
>> > there, but if it's ok in general then that's a straightforward one-line
>> > patch.
>>
>> But why can't we just rely on what the device already has on its PCI
>> config space and only ensure to disable L0s?
>
> Because we globally disable ASPM on pre-1.1 devices, because that's what
> Windows does. It makes it easier for us to figure out what level of
> support we can expect from different hardware revisions.

I see.. thanks Mathew... in that case since L1 works on all devices we
could just force enable L1 for all PCIE devices. What do you think?

  Luis
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