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From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Manyi Li <limanyi@uniontech.com>
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>,
	Bjorn Helgaas <helgaas@kernel.org>,
	bhelgaas@google.com, refactormyself@gmail.com, kw@linux.com,
	rajatja@google.com, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, Vidya Sagar <vidyas@nvidia.com>,
	rafael@kernel.org
Subject: Re: [PATCH] PCI/ASPM: Should not report ASPM support to BIOS if FADT indicates ASPM is unsupported
Date: Fri, 15 Jul 2022 09:29:45 +0100	[thread overview]
Message-ID: <20220715082945.GA10661@srcf.ucam.org> (raw)
In-Reply-To: <7305201c-eaf2-cb36-80fe-15174d3e33c7@uniontech.com>

On Fri, Jul 15, 2022 at 03:40:36PM +0800, Manyi Li wrote:

> Please see the details of this issus:
> https://bugzilla.kernel.org/show_bug.cgi?id=216245

Hmm. The only case where changing aspm_support_enabled to false should 
matter is in pcie_aspm_init_link_state(), where it looks like we'll 
potentially rewrite some registers even if aspm_disabled is true. I 
think in theory we shouldn't actually modify anything as a result, and 
the lspcis from the bug don't show any ASPM values having changed, but I 
don't trust Realtek hardware in the general case so maybe it gets upset 
here? If the proposed patch is to just set aspm_support_enabled to false 
when we see the FADT bit set then I think this is fine.

  parent reply	other threads:[~2022-07-15  8:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-13 11:26 [PATCH] PCI/ASPM: Should not report ASPM support to BIOS if FADT indicates ASPM is unsupported Manyi Li
2022-07-13 18:28 ` Bjorn Helgaas
2022-07-14  3:20   ` Kai-Heng Feng
2022-07-14  4:56     ` Matthew Garrett
     [not found]     ` <7305201c-eaf2-cb36-80fe-15174d3e33c7@uniontech.com>
2022-07-15  8:29       ` Matthew Garrett [this message]
     [not found]         ` <c8498fc1-854f-efdc-bbc8-3de67dcf6430@uniontech.com>
2022-07-15  9:32           ` Matthew Garrett
     [not found]             ` <62d14039.1c69fb81.86d3c.71c2SMTPIN_ADDED_BROKEN@mx.google.com>
2022-07-15 12:32               ` Rafael J. Wysocki
2022-07-15 12:56                 ` Rafael J. Wysocki
2022-07-15 22:49             ` Bjorn Helgaas
     [not found]     ` <62d11a02.1c69fb81.ee60c.b0efSMTPIN_ADDED_BROKEN@mx.google.com>
2022-07-15 12:24       ` Rafael J. Wysocki
2022-07-15 14:07         ` Rafael J. Wysocki
2022-08-15  9:02           ` Manyi Li
2022-08-15 18:56 ` Bjorn Helgaas

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