Re: [PATCH] PCI/ASPM: Enable L0s/L1 for removable devices when BIOS didn't configure ASPM
From: Mario Limonciello
Date: Thu May 14 2026 - 13:17:05 EST
On 5/6/26 10:27, Bjorn Helgaas wrote:
On Wed, May 06, 2026 at 10:10:47AM -0500, Mario Limonciello wrote:It sounds like you're suggesting no changes to this proposal then, right?
On 5/5/26 23:53, Mika Westerberg wrote:
On Tue, May 05, 2026 at 08:09:22PM +0200, Rafael J. Wysocki wrote:...
On Tue, May 5, 2026 at 12:53 AM Mario Limonciello
<mario.limonciello@xxxxxxx> wrote:
+ * For devicetree platforms, enable L0s and L1 by default.
+ *
+ * For removable devices (e.g., Thunderbolt/USB4), enable L0s and L1
+ * by default if BIOS didn't configure any ASPM states. This handles
+ * hotplugged devices where firmware may not have configured ASPM.
+ */
Only L1 is supported over TB/USB4 tunnel (no L0s, no L1 substates). The
PCIe endpoint and the downstream port it connects to of course can support
the full range as that's a real PCIe link.
OK - the comment should be updated but I do expect that below code
(link->aspm_support) should remain OK.
TB/USB4 are examples of removable devices but they're not the only
ones, so I think it's OK for the comment to mention L0s. In fact, it
*should* mention L0s since the code below includes L0s, and mentioning
only L1 would just be confusing.