kernel/linux.git/drivers/usb/core/hub.c, branch v6.18.21

usb: hub: Don't try to recover devices lost during warm reset.

2025-07-16T07:48:11+00:00

Hub driver warm-resets ports in SS.Inactive or Compliance mode to recover a possible connected device. The port reset code correctly detects if a connection is lost during reset, but hub driver port_event() fails to take this into account in some cases. port_event() ends up using stale values and assumes there is a connected device, and will try all means to recover it, including power-cycling the port. Details: This case was triggered when xHC host was suspended with DbC (Debug Capability) enabled and connected. DbC turns one xHC port into a simple usb debug device, allowing debugging a system with an A-to-A USB debug cable. xhci DbC code disables DbC when xHC is system suspended to D3, and enables it back during resume. We essentially end up with two hosts connected to each other during suspend, and, for a short while during resume, until DbC is enabled back. The suspended xHC host notices some activity on the roothub port, but can't train the link due to being suspended, so xHC hardware sets a CAS (Cold Attach Status) flag for this port to inform xhci host driver that the port needs to be warm reset once xHC resumes. CAS is xHCI specific, and not part of USB specification, so xhci driver tells usb core that the port has a connection and link is in compliance mode. Recovery from complinace mode is similar to CAS recovery. xhci CAS driver support that fakes a compliance mode connection was added in commit 8bea2bd37df0 ("usb: Add support for root hub port status CAS") Once xHCI resumes and DbC is enabled back, all activity on the xHC roothub host side port disappears. The hub driver will anyway think port has a connection and link is in compliance mode, and hub driver will try to recover it. The port power-cycle during recovery seems to cause issues to the active DbC connection. Fix this by clearing connect_change flag if hub_port_reset() returns -ENOTCONN, thus avoiding the whole unnecessary port recovery and initialization attempt. Cc: stable@vger.kernel.org Fixes: 8bea2bd37df0 ("usb: Add support for root hub port status CAS") Tested-by: Łukasz Bartosik Signed-off-by: Mathias Nyman Acked-by: Alan Stern Link: https://lore.kernel.org/r/20250623133947.3144608-1-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: hub: Fix flushing of delayed work used for post resume purposes

2025-06-30T13:36:00+00:00

Delayed work that prevents USB3 hubs from runtime-suspending too early needed to be flushed in hub_quiesce() to resolve issues detected on QC SC8280XP CRD board during suspend resume testing. This flushing did however trigger new issues on Raspberry Pi 3B+, which doesn't have USB3 ports, and doesn't queue any post resume delayed work. The flushed 'hub->init_work' item is used for several purposes, and is originally initialized with a 'NULL' work function. The work function is also changed on the fly, which may contribute to the issue. Solve this by creating a dedicated delayed work item for post resume work, and flush that delayed work in hub_quiesce() Cc: stable Fixes: a49e1e2e785f ("usb: hub: Fix flushing and scheduling of delayed work that tunes runtime pm") Reported-by: Mark Brown Closes: https://lore.kernel.org/linux-usb/aF5rNp1l0LWITnEB@finisterre.sirena.org.uk Signed-off-by: Mathias Nyman Tested-by: Konrad Dybcio # SC8280XP CRD Tested-by: Mark Brown Link: https://lore.kernel.org/r/20250627164348.3982628-2-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: hub: Fix flushing and scheduling of delayed work that tunes runtime pm

2025-06-26T14:57:39+00:00

Delayed work to prevent USB3 hubs from runtime-suspending immediately after resume was added in commit 8f5b7e2bec1c ("usb: hub: fix detection of high tier USB3 devices behind suspended hubs"). This delayed work needs be flushed if system suspends, or hub needs to be quiesced for other reasons right after resume. Not flushing it triggered issues on QC SC8280XP CRD board during suspend/resume testing. Fix it by flushing the delayed resume work in hub_quiesce() The delayed work item that allow hub runtime suspend is also scheduled just before calling autopm get. Alan pointed out there is a small risk that work is run before autopm get, which would call autopm put before get, and mess up the runtime pm usage order. Swap the order of work sheduling and calling autopm get to solve this. Cc: stable Fixes: 8f5b7e2bec1c ("usb: hub: fix detection of high tier USB3 devices behind suspended hubs") Reported-by: Konrad Dybcio Closes: https://lore.kernel.org/linux-usb/acaaa928-832c-48ca-b0ea-d202d5cd3d6c@oss.qualcomm.com Reported-by: Alan Stern Closes: https://lore.kernel.org/linux-usb/c73fbead-66d7-497a-8fa1-75ea4761090a@rowland.harvard.edu Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20250626130102.3639861-2-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: acpi: fix device link removal

2025-06-19T10:36:19+00:00

The device link to the USB4 host interface has to be removed manually since it's no longer auto removed. Fixes: 623dae3e7084 ("usb: acpi: fix boot hang due to early incorrect 'tunneled' USB3 device links") Cc: stable Signed-off-by: Heikki Krogerus Reviewed-by: Mika Westerberg Link: https://lore.kernel.org/r/20250611111415.2707865-1-heikki.krogerus@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: hub: fix detection of high tier USB3 devices behind suspended hubs

2025-06-19T10:36:06+00:00

USB3 devices connected behind several external suspended hubs may not be detected when plugged in due to aggressive hub runtime pm suspend. The hub driver immediately runtime-suspends hubs if there are no active children or port activity. There is a delay between the wake signal causing hub resume, and driver visible port activity on the hub downstream facing ports. Most of the LFPS handshake, resume signaling and link training done on the downstream ports is not visible to the hub driver until completed, when device then will appear fully enabled and running on the port. This delay between wake signal and detectable port change is even more significant with chained suspended hubs where the wake signal will propagate upstream first. Suspended hubs will only start resuming downstream ports after upstream facing port resumes. The hub driver may resume a USB3 hub, read status of all ports, not yet see any activity, and runtime suspend back the hub before any port activity is visible. This exact case was seen when conncting USB3 devices to a suspended Thunderbolt dock. USB3 specification defines a 100ms tU3WakeupRetryDelay, indicating USB3 devices expect to be resumed within 100ms after signaling wake. if not then device will resend the wake signal. Give the USB3 hubs twice this time (200ms) to detect any port changes after resume, before allowing hub to runtime suspend again. Cc: stable Fixes: 2839f5bcfcfc ("USB: Turn on auto-suspend for USB 3.0 hubs.") Acked-by: Alan Stern Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20250611112441.2267883-1-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

treewide, timers: Rename from_timer() to timer_container_of()

2025-06-08T07:07:37+00:00

Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com

usb: Flush altsetting 0 endpoints before reinitializating them after reset.

2025-05-21T11:11:27+00:00

usb core avoids sending a Set-Interface altsetting 0 request after device reset, and instead relies on calling usb_disable_interface() and usb_enable_interface() to flush and reset host-side of those endpoints. xHCI hosts allocate and set up endpoint ring buffers and host_ep->hcpriv during usb_hcd_alloc_bandwidth() callback, which in this case is called before flushing the endpoint in usb_disable_interface(). Call usb_disable_interface() before usb_hcd_alloc_bandwidth() to ensure URBs are flushed before new ring buffers for the endpoints are allocated. Otherwise host driver will attempt to find and remove old stale URBs from a freshly allocated new ringbuffer. Cc: stable Fixes: 4fe0387afa89 ("USB: don't send Set-Interface after reset") Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20250514132520.225345-1-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: hub: Fail fast in USB3 link power management enable path

2025-04-11T14:08:34+00:00

Enabling LPM is done in hub workqueue, often in paths handling possible link issues. So fail immediately on USB3 LPM issues and avoid hub wq from unnecessary blocking, thus allowing it to handle other port events faster. Detect errors when enabling U1/U2 link states, and return immediately if there is an issue. Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20250314142000.93090-6-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: hub: reorder USB3 link power management enable requests

2025-04-11T14:08:34+00:00

Several usb requests are needed to allow a USB3 link to enter U1/U2 hardware link power management LPM states. Reorder these requests and send the more significant and likely to succeed first. This is similar to the change done for disabling LPM Enable LPM by first sending requests to the upstream hub of the device SetPortFeature(U1_TIMEOUT) SetPortFeature(U2_TIMEOUT) These are more likely to succeed due to the shorter path, and LPM can be considered enabled as link may go to U1/U2 LPM states after those. Send the requests to the device after this, they allow the device to initialte U1/U2 link transitions. Hub can already initiate U1/U2 SetFeature(U1_ENABLE) SetFeature(U2_ENABLE) Fail fast and bail out if a requests to the device fails. This changes device initated LPM policy a bit. Device is no longer able to initiate U2 if it failed or is not allowed to initiate U1. Enabling and disabling Link power management is done as part of hub work. Avoid trying to send additional USB requests to a device when there are known issues. It just causes hub work to block for even longer. Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20250314142000.93090-5-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman

usb: hub: Don't disable LPM completely if device initiated LPM fails

2025-04-11T14:08:34+00:00

Enabling device initiated USB3 link power management (LPM) may fail for various reasons such as too long system exit latency, or link issues. These are not good reason to disable hub initiated LPM U1/U2 states, especially as it requires sending more requests over a possibly broken link, causing the hub work to block for even longer. Signed-off-by: Mathias Nyman Link: https://lore.kernel.org/r/20250314142000.93090-4-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman