commit 8a4b06d391b0a42a373808979b5028f5c84d9c6a upstream

Add the sysfs reporting file for MDS. It exposes the vulnerability and
mitigation state similar to the existing files for the other speculative
hardware vulnerabilities.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NBorislav Petkov <bp@suse.de>
Reviewed-by: NJon Masters <jcm@redhat.com>
Tested-by: NJon Masters <jcm@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Scrubbing pages on initial balloon down can take some time, especially
in nested virtualization case (nested EPT is slow). When HVM/PVH guest is
started with memory= significantly lower than maxmem=, all the extra
pages will be scrubbed before returning to Xen. But since most of them
weren't used at all at that point, Xen needs to populate them first
(from populate-on-demand pool). In nested virt case (Xen inside KVM)
this slows down the guest boot by 15-30s with just 1.5GB needed to be
returned to Xen.

Add runtime parameter to enable/disable it, to allow initially disabling
scrubbing, then enable it back during boot (for example in initramfs).
Such usage relies on assumption that a) most pages ballooned out during
initial boot weren't used at all, and b) even if they were, very few
secrets are in the guest at that time (before any serious userspace
kicks in).
Convert CONFIG_XEN_SCRUB_PAGES to CONFIG_XEN_SCRUB_PAGES_DEFAULT (also
enabled by default), controlling default value for the new runtime
switch.
Signed-off-by: NMarek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>

Export device state to sysfs to allow for easier get device state.
Signed-off-by: NJoe Jin <joe.jin@oracle.com>
Reviewed-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: NBoris Ostrovsky <boris.ostrovsky@oracle.com>

Persistent grants are allocated until a threshold per ring is being
reached. Those grants won't be freed until the ring is being destroyed
meaning there will be resources kept busy which might no longer be
used.

Instead of freeing only persistent grants until the threshold is
reached add a timestamp and remove all persistent grants not having
been in use for a minute.
Signed-off-by: NJuergen Gross <jgross@suse.com>
Reviewed-by: NRoger Pau Monné <roger.pau@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

This reverts the commit - "b93f7712 - f2fs: remove writepages lock"
to fix the drop in sequential read throughput.

Test: ./tiotest -t 32 -d /data/tio_tmp -f 32 -b 524288 -k 1 -k 3 -L
device: UFS

Before -
read throughput: 185 MB/s
total read requests: 85177 (of these ~80000 are 4KB size requests).
total write requests: 2546 (of these ~2208 requests are written in 512KB).

After -
read throughput: 758 MB/s
total read requests: 2417 (of these ~2042 are 512KB reads).
total write requests: 2701 (of these ~2034 requests are written in 512KB).
Signed-off-by: NSahitya Tummala <stummala@codeaurora.org>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Signed-off-by: NRashmica Gupta <rashmica.g@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The systems of type MSN21xx, MSN201x have a slight difference from the
default reset cause bits description, it uses reset_hotswap_or_halt
instead of reset_hotswap_or_wd. New attribute is documented.
Signed-off-by: NVadim Pasternak <vadimp@mellanox.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

Being able to find the numa_node for a device is useful for userspace
drivers (DPDK) and also for diagnosing performance issues.  This makes
vmbus similar to pci.
Signed-off-by: NStephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: NK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

When utilising multiple instantiations of a UVC gadget on a composite
device, there is no clear method to link a particular configuration to
its respective video node.

Provide a means for identifying the correct video node by exposing the
name of the function configuration through sysfs.
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NKieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>

e-mail received from Silicon Lab to confirm that the licensing
isn't a problem.

"
Dear Maxime Roussin-Belanger,

The LUX calculation code only works with Si1133.
As long as the software is used with Silicon Lab's sensor product,
I don't see any problem.

Regards,
Tony
"
Signed-off-by: NMaxime Roussin-Bélanger <maxime.roussinbelanger@gmail.com>
Reviewed-by: NJean-Francois Dagenais <jeff.dagenais@gmail.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Signed-off-by: NMaxime Roussin-Bélanger <maxime.roussinbelanger@gmail.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

This patch adds support for the ISL29501 Time of Flight sensor.
Signed-off-by: NMathieu Othacehe <m.othacehe@gmail.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Add new channel type support for phase.

This channel may be used by Time-of-flight sensors to express the
phase difference between emitted and received signals. Those sensor
will then use the phase shift of return signals to approximate the
distance to objects.
Signed-off-by: NMathieu Othacehe <m.othacehe@gmail.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

Add sysfs attributes for rootport statistics (that are cumulative of all
the ERR_* messages seen on this PCI hierarchy).
Signed-off-by: NRajat Jain <rajatja@google.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Add sysfs attributes to provide total and breakdown of the AERs seen,
into different type of correctable, fatal and nonfatal errors:

  /sys/bus/pci/devices/<dev>/aer_dev_correctable
  /sys/bus/pci/devices/<dev>/aer_dev_fatal
  /sys/bus/pci/devices/<dev>/aer_dev_nonfatal
Signed-off-by: NRajat Jain <rajatja@google.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

Add tracking of REQ_OP_DISCARD ios to the partition statistics and
append them to the various stat files in /sys as well as
/proc/diskstats.  These are tracked with the same four stats as reads
and writes:

Number of discard ios completed.
Number of discard ios merged
Number of discard sectors completed
Milliseconds spent on discard requests

This is done via adding a new STAT_DISCARD define to genhd.h and then
using it to index that stat field for discard requests.

tj: Refreshed on top of v4.17 and other previous updates.
Signed-off-by: NMichael Callahan <michaelcallahan@fb.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Andy Newell <newella@fb.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Signed-off-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NPavel Machek <pavel@ucw.cz>
Reviewed-by: NNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: NMark Brown <broonie@kernel.org>

User Accelerated Function Unit sub feature exposes the MMIO region of
the AFU. After valid PR bitstream is programmed and the port is enabled,
then this MMIO region could be accessed.

This patch adds support to enumerate the AFU MMIO region and expose it
to userspace via mmap file operation. Below interfaces are exposed to user:

Sysfs interface:
* /sys/class/fpga_region/<regionX>/<dfl-port.x>/afu_id
  Read-only. Indicate which PR bitstream is programmed to this AFU.

Ioctl interfaces:
* DFL_FPGA_PORT_GET_INFO
  Provide info to userspace on the number of supported region.
  Only UAFU region is supported now.

* DFL_FPGA_PORT_GET_REGION_INFO
  Provide region information, including access permission, region size,
  offset from the start of device fd.
Signed-off-by: NTim Whisonant <tim.whisonant@intel.com>
Signed-off-by: NEnno Luebbers <enno.luebbers@intel.com>
Signed-off-by: NShiva Rao <shiva.rao@intel.com>
Signed-off-by: NChristopher Rauer <christopher.rauer@intel.com>
Signed-off-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: NWu Hao <hao.wu@intel.com>
Acked-by: NAlan Tull <atull@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The port header register set is always present for port, it is mainly
for capability, control and status of the ports that AFU connected to.

This patch implements header sub feature support. Below user interfaces
are created by this patch.

Sysfs interface:
* /sys/class/fpga_region/<regionX>/<dfl-port.x>/id
  Read-only. Port ID.

Ioctl interface:
* DFL_FPGA_PORT_RESET
  Reset the FPGA Port and its AFU.
Signed-off-by: NTim Whisonant <tim.whisonant@intel.com>
Signed-off-by: NEnno Luebbers <enno.luebbers@intel.com>
Signed-off-by: NShiva Rao <shiva.rao@intel.com>
Signed-off-by: NChristopher Rauer <christopher.rauer@intel.com>
Signed-off-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: NWu Hao <hao.wu@intel.com>
Acked-by: NAlan Tull <atull@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The Header Register set is always present for FPGA Management Engine (FME),
this patch implements init and uinit function for header sub feature and
introduces several read-only sysfs interfaces for the capability and
status.

Sysfs interfaces:
* /sys/class/fpga_region/<regionX>/<dfl-fme.x>/ports_num
  Read-only. Number of ports implemented

* /sys/class/fpga_region/<regionX>/<dfl-fme.x>/bitstream_id
  Read-only. Bitstream (static FPGA region) identifier number. It contains
  the detailed version and other information of this static FPGA region.

* /sys/class/fpga_region/<regionX>/<dfl-fme.x>/bitstream_metadata
  Read-only. Bitstream (static FPGA region) meta data. It contains the
  synthesis date, seed and other information of this static FPGA region.
Signed-off-by: NTim Whisonant <tim.whisonant@intel.com>
Signed-off-by: NEnno Luebbers <enno.luebbers@intel.com>
Signed-off-by: NShiva Rao <shiva.rao@intel.com>
Signed-off-by: NChristopher Rauer <christopher.rauer@intel.com>
Signed-off-by: NKang Luwei <luwei.kang@intel.com>
Signed-off-by: NXiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: NWu Hao <hao.wu@intel.com>
Acked-by: NAlan Tull <atull@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch introduces a compat_id pointer member and sysfs interface
for each fpga region, similar as compat_id for fpga manager, it allows
applications to read the per region compat_id for compatibility
checking before other actions on this fpga-region (e.g. PR).
Signed-off-by: NWu Hao <hao.wu@intel.com>
Acked-by: NAlan Tull <atull@kernel.org>
Acked-by: NMoritz Fischer <mdf@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch adds status sysfs interface for fpga manager, it's a
read only interface which allows user to get fpga manager status,
including full/partial reconfiguration error and other status
information. It adds a status callback to fpga_manager_ops too,
allows each fpga_manager driver to define its own method to
collect latest status from hardware.

The following sysfs file is created:
* /sys/class/fpga_manager/<fpga>/status
  Return status of fpga manager, including reconfiguration errors.
Signed-off-by: NWu Hao <hao.wu@intel.com>
Acked-by: NAlan Tull <atull@kernel.org>
Acked-by: NMoritz Fischer <mdf@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Now that we can dynamically switch between contiguous memory and
SG table depending on the trace buffer size, provide the support
for selecting an appropriate buffer size.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: NSuzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introduce the 'l1tf=' kernel command line option to allow for boot-time
switching of mitigation that is used on processors affected by L1TF.

The possible values are:

  full
	Provides all available mitigations for the L1TF vulnerability. Disables
	SMT and enables all mitigations in the hypervisors. SMT control via
	/sys/devices/system/cpu/smt/control is still possible after boot.
	Hypervisors will issue a warning when the first VM is started in
	a potentially insecure configuration, i.e. SMT enabled or L1D flush
	disabled.

  full,force
	Same as 'full', but disables SMT control. Implies the 'nosmt=force'
	command line option. sysfs control of SMT and the hypervisor flush
	control is disabled.

  flush
	Leaves SMT enabled and enables the conditional hypervisor mitigation.
	Hypervisors will issue a warning when the first VM is started in a
	potentially insecure configuration, i.e. SMT enabled or L1D flush
	disabled.

  flush,nosmt
	Disables SMT and enables the conditional hypervisor mitigation. SMT
	control via /sys/devices/system/cpu/smt/control is still possible
	after boot. If SMT is reenabled or flushing disabled at runtime
	hypervisors will issue a warning.

  flush,nowarn
	Same as 'flush', but hypervisors will not warn when
	a VM is started in a potentially insecure configuration.

  off
	Disables hypervisor mitigations and doesn't emit any warnings.

Default is 'flush'.

Let KVM adhere to these semantics, which means:

  - 'lt1f=full,force'	: Performe L1D flushes. No runtime control
    			  possible.

  - 'l1tf=full'
  - 'l1tf-flush'
  - 'l1tf=flush,nosmt'	: Perform L1D flushes and warn on VM start if
			  SMT has been runtime enabled or L1D flushing
			  has been run-time enabled
			  
  - 'l1tf=flush,nowarn'	: Perform L1D flushes and no warnings are emitted.
  
  - 'l1tf=off'		: L1D flushes are not performed and no warnings
			  are emitted.

KVM can always override the L1D flushing behavior using its 'vmentry_l1d_flush'
module parameter except when lt1f=full,force is set.

This makes KVM's private 'nosmt' option redundant, and as it is a bit
non-systematic anyway (this is something to control globally, not on
hypervisor level), remove that option.

Add the missing Documentation entry for the l1tf vulnerability sysfs file
while at it.
Signed-off-by: NJiri Kosina <jkosina@suse.cz>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Tested-by: NJiri Kosina <jkosina@suse.cz>
Reviewed-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: NJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142323.202758176@linutronix.de

The ME FW version is constantly used by detection and update tools.
To improve the reliability and simplify these tools provide
a sysfs interface to access version of the platform ME firmware
in the following format:
<platform>:<major>.<minor>.<milestone>.<build>.
There can be up to three such blocks for different FW components.
Signed-off-by: NAlexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: NTomas Winkler <tomas.winkler@intel.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

DisplayPort USB Type-C Alt Mode allows DisplayPort displays
and adapters to be attached to the USB Type-C ports on the
system.
Signed-off-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Introducing a simple bus for the alternate modes. Bus allows
binding drivers to the discovered alternate modes the
partners support.
Signed-off-by: NHeikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: NHans de Goede <hdegoede@redhat.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: NAmritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a "type" device attribute and a "GNSS_TYPE" uevent variable which
can be used to determine the type of a GNSS receiver. The currently
identified types reflect the protocol(s) supported by a receiver:

	"NMEA"	NMEA 0183
	"SiRF"	SiRF Binary
	"UBX"	UBX

Note that both SiRF and UBX type receivers typically support a subset of
NMEA 0183 with vendor extensions (e.g. to allow switching to the vendor
protocol).
Signed-off-by: NJohan Hovold <johan@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Provide a command line and a sysfs knob to control SMT.

The command line options are:

 'nosmt':	Enumerate secondary threads, but do not online them
 		
 'nosmt=force': Ignore secondary threads completely during enumeration
 		via MP table and ACPI/MADT.

The sysfs control file has the following states (read/write):

 'on':		 SMT is enabled. Secondary threads can be freely onlined
 'off':		 SMT is disabled. Secondary threads, even if enumerated
 		 cannot be onlined
 'forceoff':	 SMT is permanentely disabled. Writes to the control
 		 file are rejected.
 'notsupported': SMT is not supported by the CPU

The command line option 'nosmt' sets the sysfs control to 'off'. This
can be changed to 'on' to reenable SMT during runtime.

The command line option 'nosmt=force' sets the sysfs control to
'forceoff'. This cannot be changed during runtime.

When SMT is 'on' and the control file is changed to 'off' then all online
secondary threads are offlined and attempts to online a secondary thread
later on are rejected.

When SMT is 'off' and the control file is changed to 'on' then secondary
threads can be onlined again. The 'off' -> 'on' transition does not
automatically online the secondary threads.

When the control file is set to 'forceoff', the behaviour is the same as
setting it to 'off', but the operation is irreversible and later writes to
the control file are rejected.

When the control status is 'notsupported' then writes to the control file
are rejected.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Reviewed-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: NIngo Molnar <mingo@kernel.org>

Add documentation for mlxreg-io platform driver sysfs interfaces to allow
user space access for system resets control, reset causes monitoring,
programmable devices version reading and device selection control.
Signed-off-by: NVadim Pasternak <vadimp@mellanox.com>
Signed-off-by: NDarren Hart (VMware) <dvhart@infradead.org>

This file doesn't exist anymore:
	Documentation/cpu-freq/user-guide.txt

As the ABI already points to Documentation/cpu-freq, just
remove the broken link and the associated text.
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: NJonathan Corbet <corbet@lwn.net>

The script:
	./scripts/documentation-file-ref-check --fix

Gives multiple hints for broken references on some files.
Manually use the one that applies for some files.
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NJames Morris <james.morris@microsoft.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: NJonathan Corbet <corbet@lwn.net>

The first subfolder is rfkill0, hence rfkillX (X >= 0).
Also fix two trivial typos.
Signed-off-by: NPeter Meerwald-Stadler <pmeerw@pmeerw.net>
Signed-off-by: NJohannes Berg <johannes@sipsolutions.net>

Add new channel type for relative position on a pad.

These type of analog sensor offers the position of a pen
on a touchpad, and is represented as a voltage, which can be
converted to a position on X and Y axis on the pad.
The channel will hand the relative position on the pad in both directions.

The channel can then be consumed by a touchscreen driver or
read as-is for a raw indication of the touchpen on a touchpad.
Signed-off-by: NEugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

The "Clear Error Unit" may be smaller than the ECC unit size on some
devices. For example, poison may be tracked at 64-byte alignment even
though the ECC unit is larger. Unless / until the ACPI specification
provides a non-ambiguous way to communicate this property do not expose
this to userspace.

Software that had been using this property must already be prepared for
the case where the property is not provided on older kernels, so it is
safe to remove this attribute.
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Currently we see a kernel-oops reported on Power-9 while attaching a
context to an AFU, with radix-mode and sysfs attr 'prefault_mode' set
to anything other than 'none'. The backtrace of the oops is of this
form:

  Unable to handle kernel paging request for data at address 0x00000080
  Faulting instruction address: 0xc00800000bcf3b20
  cpu 0x1: Vector: 300 (Data Access) at [c00000037f003800]
      pc: c00800000bcf3b20: cxl_load_segment+0x178/0x290 [cxl]
      lr: c00800000bcf39f0: cxl_load_segment+0x48/0x290 [cxl]
      sp: c00000037f003a80
     msr: 9000000000009033
     dar: 80
   dsisr: 40000000
    current = 0xc00000037f280000
    paca    = 0xc0000003ffffe600   softe: 3        irq_happened: 0x01
      pid   = 3529, comm = afp_no_int
  <snip>
  cxl_prefault+0xfc/0x248 [cxl]
  process_element_entry_psl9+0xd8/0x1a0 [cxl]
  cxl_attach_dedicated_process_psl9+0x44/0x130 [cxl]
  native_attach_process+0xc0/0x130 [cxl]
  afu_ioctl+0x3f4/0x5e0 [cxl]
  do_vfs_ioctl+0xdc/0x890
  ksys_ioctl+0x68/0xf0
  sys_ioctl+0x40/0xa0
  system_call+0x58/0x6c

The issue is caused as on Power-8 the AFU attr 'prefault_mode' was
used to improve initial storage fault performance by prefaulting
process segments. However on Power-9 with radix mode we don't have
Storage-Segments that we can prefault. Also prefaulting process Pages
will be too costly and fine-grained.

Hence, since the prefaulting mechanism doesn't makes sense of
radix-mode, this patch updates prefault_mode_store() to not allow any
other value apart from CXL_PREFAULT_NONE when radix mode is enabled.

Fixes: f24be42a ("cxl: Add psl9 specific code")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: NVaibhav Jain <vaibhav@linux.ibm.com>
Acked-by: NFrederic Barrat <fbarrat@linux.vnet.ibm.com>
Acked-by: NAndrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The file is called "features", not "feature".
Signed-off-by: NEric Biggers <ebiggers@google.com>
Reviewed-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>

Currently, the USB hub core waits for 50 ms after enumerating the
device. This was added to help "some high speed devices" to
enumerate (b789696a "[PATCH] USB: relax usbcore reset timings").

On some devices, the time-to-active is important, so we provide
a per-port option to reduce the time to what the USB specification
requires: 10 ms.
Signed-off-by: NNicolas Boichat <drinkcat@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

The "old" enumeration scheme is considerably faster (it takes
~244ms instead of ~356ms to get the descriptor).

It is currently only possible to use the old scheme globally
(/sys/module/usbcore/parameters/old_scheme_first), which is not
desirable as the new scheme was introduced to increase compatibility
with more devices.

However, in our case, we care about time-to-active for a specific
USB device (which we make the firmware for), on a specific port
(that is pogo-pin based: not a standard USB port). This new
sysfs option makes it possible to use the old scheme on a single
port only.
Signed-off-by: NNicolas Boichat <drinkcat@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>