From: sashiko-bot@kernel.org
To: "Anthony Ruhier" <aruhier@mailbox.org>
Cc: linux-pci@vger.kernel.org
Subject: Re: [PATCH] PCI: Disable LTR on Qualcomm WCN7850 [17cb:1107] to allow ASPM L1.2
Date: Fri, 23 Oct 2026 17:55:20 +0000 [thread overview]
Message-ID: <sashiko-outbox-183023@kernel.org> (raw)
In-Reply-To: <20261023-quick-wcn7850-v1-1-9a139b9b2c8e@mailbox.org>
> From: Anthony Ruhier <aruhier@mailbox.org>
>
> The WCN7850 Wifi/BT card, found in several Snapdragon X laptops, never
> enters ASPM L1.2 when LTR is enabled. Its firmware reads the
> LTR_L1.2_THRESHOLD set at enumeration and reports an LTR value just
> below it, so the L1.2 entry condition is never met and the link stays in
> L1.1.
>
> Windows does not set LTR Mechanism Enable for this device (verified by
> dumping the ACPI tables), and the link idles in L1.2 normally.
>
> Replicate the same behavior: clear PCI_EXP_DEVCTL2_LTR_EN for WCN7850 at
> enumeration and again on resume, as the LTR state is restored there.
>
> On a Lenovo Yoga Slim 7x (X1E80100) this allows the link to reach L1.2
> and reduces idle power by about 70 mW.
>
> Signed-off-by: Anthony Ruhier <aruhier@mailbox.org>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261023-quick-wcn7850-v1-1-9a139b9b2c8e@mailbox.org?part=1
next prev parent reply other threads:[~2026-10-23 17:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-23 17:39 [PATCH] PCI: Disable LTR on Qualcomm WCN7850 [17cb:1107] to allow ASPM L1.2 Anthony Ruhier via B4 Relay
2026-10-23 17:39 ` Anthony Ruhier
2026-10-23 17:55 ` sashiko-bot [this message]
2026-10-23 18:20 ` Bjorn Helgaas
2026-10-23 21:49 ` Anthony Ruhier
2026-10-25 21:16 ` Anthony Ruhier
2026-10-26 7:25 ` Manivannan Sadhasivam
2026-10-26 7:53 ` Manivannan Sadhasivam
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