A recent cleanup went a bit too far and dropped clearing the cycle bit
of link TRBs, so it stays different from the rest of the ring half of
the time. Then a race occurs: if the xHC reaches such link TRB before
more commands are queued, the link's cycle bit unintentionally matches
the xHC's cycle so it follows the link and waits for further commands.
If more commands are queued before the xHC gets there, inc_enq() flips
the bit so the xHC later sees a mismatch and stops executing commands.

This function is called before suspend and 50% of times after resuming
the xHC is doomed to get stuck sooner or later. Then some Stop Endpoint
command fails to complete in 5 seconds and this shows up

xhci_hcd 0000:00:10.0: xHCI host not responding to stop endpoint command
xhci_hcd 0000:00:10.0: xHCI host controller not responding, assume dead
xhci_hcd 0000:00:10.0: HC died; cleaning up

followed by loss of all USB decives on the affected bus. That's if you
are lucky, because if Set Deq gets stuck instead, the failure is silent.

Likely responsible for kernel bug 219824. I found this while searching
for possible causes of that regression and reproduced it locally before
hearing back from the reporter. To repro, simply wait for link cycle to
become set (debugfs), then suspend, resume and wait. To accelerate the
failure I used a script which repeatedly starts and stops a UVC camera.

Some HCs get fully reinitialized on resume and they are not affected.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=219824
Fixes: 36b972d4b7ce ("usb: xhci: improve xhci_clear_command_ring()")
Cc: stable@vger.kernel.org
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250304113147.3322584-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When adding support for USB3-over-USB4 tunnelling detection, a check
for an Intel-specific capability was added. This capability, which
goes by ID 206, is used without any check that we are actually
dealing with an Intel host.

As it turns out, the Cadence XHCI controller *also* exposes an
extended capability numbered 206 (for unknown purposes), but of
course doesn't have the Intel-specific registers that the tunnelling
code is trying to access. Fun follows.

The core of the problems is that the tunnelling code blindly uses
vendor-specific capabilities without any check (the Intel-provided
documentation I have at hand indicates that 192-255 are indeed
vendor-specific).

Restrict the detection code to Intel HW for real, preventing any
further explosion on my (non-Intel) HW.

Cc: stable <stable@kernel.org>
Fixes: 948ce83fbb7df ("xhci: Add USB4 tunnel detection for USB3 devices on Intel hosts")
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250227194529.2288718-1-maz@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Raspberry Pi is a major user of those chips and they discovered a bug -
when the end of a transfer ring segment is reached, up to four TRBs can
be prefetched from the next page even if the segment ends with link TRB
and on page boundary (the chip claims to support standard 4KB pages).

It also appears that if the prefetched TRBs belong to a different ring
whose doorbell is later rung, they may be used without refreshing from
system RAM and the endpoint will stay idle if their cycle bit is stale.

Other users complain about IOMMU faults on x86 systems, unsurprisingly.

Deal with it by using existing quirk which allocates a dummy page after
each transfer ring segment. This was seen to resolve both problems. RPi
came up with a more efficient solution, shortening each segment by four
TRBs, but it complicated the driver and they ditched it for this quirk.

Also rename the quirk and add VL805 device ID macro.

Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Link: https://github.com/raspberrypi/linux/issues/4685
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=215906
CC: stable@vger.kernel.org
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250225095927.2512358-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Some Renesas HCs require firmware upload to work, this is handled by the
xhci_pci_renesas driver. Other variants of those chips load firmware from
a SPI flash and are ready to work with xhci_pci alone.

A refactor merged in v6.12 broke the latter configuration so that users
are finding their hardware ignored by the normal driver and are forced to
enable the firmware loader which isn't really necessary on their systems.

Let xhci_pci work with those chips as before when the firmware loader is
disabled by kernel configuration.

Fixes: 25f51b76f90f ("xhci-pci: Make xhci-pci-renesas a proper modular driver")
Cc: stable <stable@kernel.org>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219616
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219726
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Tested-by: Nicolai Buchwitz <nb@tipi-net.de>
Link: https://lore.kernel.org/r/20250128104529.58a79bfc@foxbook
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

LS7A EHCI controller doesn't have extended capabilities, so the EECP
(EHCI Extended Capabilities Pointer) field of HCCPARAMS register should
be 0x0, but it reads as 0xa0 now. This is a hardware flaw and will be
fixed in future, now just clear the EECP field to avoid error messages
on boot:

......
[    0.581675] pci 0000:00:04.1: EHCI: unrecognized capability ff
[    0.581699] pci 0000:00:04.1: EHCI: unrecognized capability ff
[    0.581716] pci 0000:00:04.1: EHCI: unrecognized capability ff
[    0.581851] pci 0000:00:04.1: EHCI: unrecognized capability ff
......
[    0.581916] pci 0000:00:05.1: EHCI: unrecognized capability ff
[    0.581951] pci 0000:00:05.1: EHCI: unrecognized capability ff
[    0.582704] pci 0000:00:05.1: EHCI: unrecognized capability ff
[    0.582799] pci 0000:00:05.1: EHCI: unrecognized capability ff
......

Cc: stable <stable@kernel.org>
Signed-off-by: Baoqi Zhang <zhangbaoqi@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Link: https://lore.kernel.org/r/20250202124935.480500-1-chenhuacai@loongson.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull driver core and debugfs updates from Greg KH:
 "Here is the big set of driver core and debugfs updates for 6.14-rc1.

  Included in here is a bunch of driver core, PCI, OF, and platform rust
  bindings (all acked by the different subsystem maintainers), hence the
  merge conflict with the rust tree, and some driver core api updates to
  mark things as const, which will also require some fixups due to new
  stuff coming in through other trees in this merge window.

  There are also a bunch of debugfs updates from Al, and there is at
  least one user that does have a regression with these, but Al is
  working on tracking down the fix for it. In my use (and everyone
  else's linux-next use), it does not seem like a big issue at the
  moment.

  Here's a short list of the things in here:

   - driver core rust bindings for PCI, platform, OF, and some i/o
     functions.

     We are almost at the "write a real driver in rust" stage now,
     depending on what you want to do.

   - misc device rust bindings and a sample driver to show how to use
     them

   - debugfs cleanups in the fs as well as the users of the fs api for
     places where drivers got it wrong or were unnecessarily doing
     things in complex ways.

   - driver core const work, making more of the api take const * for
     different parameters to make the rust bindings easier overall.

   - other small fixes and updates

  All of these have been in linux-next with all of the aforementioned
  merge conflicts, and the one debugfs issue, which looks to be resolved
  "soon""

* tag 'driver-core-6.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (95 commits)
  rust: device: Use as_char_ptr() to avoid explicit cast
  rust: device: Replace CString with CStr in property_present()
  devcoredump: Constify 'struct bin_attribute'
  devcoredump: Define 'struct bin_attribute' through macro
  rust: device: Add property_present()
  saner replacement for debugfs_rename()
  orangefs-debugfs: don't mess with ->d_name
  octeontx2: don't mess with ->d_parent or ->d_parent->d_name
  arm_scmi: don't mess with ->d_parent->d_name
  slub: don't mess with ->d_name
  sof-client-ipc-flood-test: don't mess with ->d_name
  qat: don't mess with ->d_name
  xhci: don't mess with ->d_iname
  mtu3: don't mess wiht ->d_iname
  greybus/camera - stop messing with ->d_iname
  mediatek: stop messing with ->d_iname
  netdevsim: don't embed file_operations into your structs
  b43legacy: make use of debugfs_get_aux()
  b43: stop embedding struct file_operations into their objects
  carl9170: stop embedding file_operations into their objects
  ...

After commit c141ecc3cecd ("of: Warn when of_property_read_bool() is
used on non-boolean properties") was added, the following warning is
observed for the Tegra XHCI driver ...

 OF: /bus@0/usb@3610000: Read of boolean property 'power-domains' with
     a value.

Previously, of_property_read_bool() was used to determine if a property
was present but has now been replaced by of_property_present(). The
warning is meant to prevent new users but this user existed before the
change was made. Fix this by updating the Tegra XHCI driver to use
of_property_present() function to determine if the 'power-domains'
property is present.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20250116153829.477360-1-jonathanh@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add support compatible ID PNP0D15 which declare that the xHCI
controller doesn't support standard debug capability.

Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/20250116125141.25856-1-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Replace ternary (condition ? "enable" : "disable") syntax with helpers
from string_choices.h because:
1. Simple function call with one argument is easier to read.  Ternary
   operator has three arguments and with wrapping might lead to quite
   long code.
2. Is slightly shorter thus also easier to read.
3. It brings uniformity in the text - same string.
4. Allows deduping by the linker, which results in a smaller binary
   file.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250114-str-enable-disable-usb-v1-2-c8405df47c19@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

use debugs_{creat_file,get}_aux() instead

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Link: https://lore.kernel.org/r/20250112080705.141166-14-viro@zeniv.linux.org.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>