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When a USB device is connected to the OTG port, the tegra_xhci_id_work()
routine transitions the PHY to host mode and calls xhci_hub_control()
with the SetPortFeature command to enable port power.
In certain cases, the XHCI controller may be in a low-power state
when this operation occurs. If xhci_hub_control() is invoked while
the controller is suspended, the PORTSC register may return 0xFFFFFFFF,
indicating a read failure. This causes xhci_hc_died() to be triggered,
leading to host controller shutdown.
Example backtrace:
[ 105.445736] Workqueue: events tegra_xhci_id_work
[ 105.445747] dump_backtrace+0x0/0x1e8
[ 105.445759] xhci_hc_died.part.48+0x40/0x270
[ 105.445769] tegra_xhci_set_port_power+0xc0/0x240
[ 105.445774] tegra_xhci_id_work+0x130/0x240
To prevent this, ensure the controller is fully resumed before
interacting with hardware registers by calling pm_runtime_get_sync()
prior to the host mode transition and xhci_hub_control().
Fixes: f836e78430 ("usb: xhci-tegra: Add OTG support")
Cc: stable <stable@kernel.org>
Signed-off-by: Jim Lin <jilin@nvidia.com>
Signed-off-by: Wayne Chang <waynec@nvidia.com>
Link: https://lore.kernel.org/r/20250422114001.126367-1-waynec@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.