How it's supposed to work:
--------------------------

USB 2.0 Link PM is a lower power state that some newer USB 2.0 devices
support.  USB 3.0 devices certified by the USB-IF are required to
support it if they are plugged into a USB 2.0 only port, or a USB 2.0
cable is used.  USB 2.0 Link PM requires both a USB device and a host
controller that supports USB 2.0 hardware-enabled LPM.

USB 2.0 Link PM is designed to be enabled once by software, and the host
hardware handles transitions to the L1 state automatically.  The premise
of USB 2.0 Link PM is to be able to put the device into a lower power
link state when the bus is idle or the device NAKs USB IN transfers for
a specified amount of time.

...but hardware is broken:
--------------------------

It turns out many USB 3.0 devices claim to support USB 2.0 Link PM (by
setting the LPM bit in their USB 2.0 BOS descriptor), but they don't
actually implement it correctly.  This manifests as the USB device
refusing to respond to transfers when it is plugged into a USB 2.0 only
port under the Haswell-ULT/Lynx Point LP xHCI host.

These devices pass the xHCI driver's simple test to enable USB 2.0 Link
PM, wait for the port to enter L1, and then bring it back into L0.  They
only start to break when L1 entry is interleaved with transfers.

Some devices then fail to respond to the next control transfer (usually
a Set Configuration).  This results in devices never enumerating.

Other mass storage devices (such as a later model Western Digital My
Passport USB 3.0 hard drive) respond fine to going into L1 between
control transfers.  They ACK the entry, come out of L1 when the host
needs to send a control transfer, and respond properly to those control
transfers.  However, when the first READ10 SCSI command is sent, the
device NAKs the data phase while it's reading from the spinning disk.
Eventually, the host requests to put the link into L1, and the device
ACKs that request.  Then it never responds to the data phase of the
READ10 command.  This results in not being able to read from the drive.

Some mass storage devices (like the Corsair Survivor USB 3.0 flash
drive) are well behaved.  They ACK the entry into L1 during control
transfers, and when SCSI commands start coming in, they NAK the requests
to go into L1, because they need to be at full power.

Not all USB 3.0 devices advertise USB 2.0 link PM support.  My Point
Grey USB 3.0 webcam advertises itself as a USB 2.1 device, but doesn't
have a USB 2.0 BOS descriptor, so we don't enable USB 2.0 Link PM.  I
suspect that means the device isn't certified.

What do we do about it?
-----------------------

There's really no good way for the kernel to test these devices.
Therefore, the kernel needs to disable USB 2.0 Link PM by default, and
distros will have to enable it by writing 1 to the sysfs file
/sys/bus/usb/devices/../power/usb2_hardware_lpm.  Rip out the xHCI Link
PM test, since it's not sufficient to detect these buggy devices, and
don't automatically enable LPM after the device is addressed.

This patch should be backported to kernels as old as 3.11, that
contain the commit a558ccdc "usb: xhci:
add USB2 Link power management BESL support".  Without this fix, some
USB 3.0 devices will not enumerate or work properly under USB 2.0 ports
on Haswell-ULT systems.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

To enable USB 2.0 Link Power Management (LPM), the xHCI host controller
needs the device slot ID to generate the device address used in L1 entry
tokens.  That information is set in the L1 device slot ID field of the
USB 2.0 LPM registers.

Currently, the L1 device slot ID is overwritten when the xHCI driver
initiates the software test of USB 2.0 Link PM in
xhci_usb2_software_lpm_test.  It is never cleared when USB 2.0 Link PM
is disabled for the device.  That should be harmless, because the
Hardware LPM Enable (HLE) bit is cleared when USB 2.0 Link PM is
disabled, so the host should not pay attention to the slot ID.

This patch should have no effect on host behavior, but since
xhci_usb2_software_lpm_test is going away in an upcoming bug fix patch,
we need to move that code to the function that enables and disables USB
2.0 Link PM.

This patch should be backported to kernels as old as 3.11, that contain
the commit a558ccdc "usb: xhci: add USB2
Link power management BESL support".  The upcoming bug fix patch is also
marked for that stable kernel.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

Before the USB core resets a device, we need to disable the L1 timeout
for the roothub, if USB 2.0 Link PM is enabled.  Otherwise the port may
transition into L1 in between descriptor fetches, before we know if the
USB device descriptors changed.  LPM will be re-enabled after the
full device descriptors are fetched, and we can confirm the device still
supports USB 2.0 LPM after the reset.

We don't need to wait for the USB device to exit L1 before resetting the
device, since the xHCI roothub port diagrams show a transition to the
Reset state from any of the Ux states (see Figure 34 in the 2012-08-14
xHCI specification update).

This patch should be backported to kernels as old as 3.2, that contain
the commit 65580b43 "xHCI: set USB2
hardware LPM".  That was the first commit to enable USB 2.0
hardware-driven Link Power Management.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable@vger.kernel.org

The non-DT for EXYNOS SoCs is not supported from v3.11.
Thus, there is no need to support non-DT for Exynos OHCI driver.

The 'include/linux/platform_data/usb-ohci-exynos.h' file has been
used for non-DT support. Thus, the 'usb-ohci-exynos.h' file can
be removed.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Remove the use of local_irq_save() and IRQF_DISABLED, no longer needed since
interrupt handlers are always run with interrupts disabled on the
current CPU.

Tested successfully with 3.12.0-rc4 on my PC. Didn't find
any issue because of this change.
Signed-off-by: Michael Opdenacker <michael.opdenacker@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch changes the initial delay before the startup of a newly
scheduled isochronous stream.  Currently the stream doesn't start
for at least 5 ms (40 microframes).  This value is just an estimate;
it has no real justification.

Instead, we can start the stream as soon as possible after the
scheduling computations are complete.  Essentially this requires
nothing more than reading the frame counter after the stream is
scheduled, instead of before.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch continues the scheduling changes in ehci-hcd by adding a
table to store the bandwidth allocation below each TT.  This will
speed up the scheduling code, as it will no longer need to read
through the entire schedule to compute the bandwidth currently in use.

Properly speaking, the FS/LS budget calculations should be done in
terms of full-speed bytes per microframe, as described in the USB-2
spec.  However the driver currently uses microseconds per microframe,
and the scheduling code isn't robust enough at this point to change
over.  For the time being, we leave the calculations as they are.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This reverts commit 476e4bf9.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

This reverts commit 056ca85d.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

This reverts commit 19d33943.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

This reverts commit 86a63f10.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

This reverts commit 018258b4.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

This reverts commit fea0896f.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

This reverts commit 36a87587.

Manjunath is no longer at Linaro, the email address bounces.  Given
that, and the fact that others have reported problems with these
patches, I'm reverting them until someone from Linaro who can SUPPORT
THEM submits them.

I will no longer accept patches from linaro.com developers unless a
senior Linaro developer has signed off on them, which did not happen
with this patch set.
Reported-by: Olof Johansson <olof@lixom.net>
Cc: Manjunath Goudar <manjunath.goudar@linaro.org>
Cc: Manjunath Goudar <csmanjuvijay@gmail.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

including:

- removing of trailing whitespace
- removing spaces before array indexing (foo [] to foo[])
- reindention of a switch-case block
- spaces to tabs
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Make sure to return errors from tiocmget rather than rely on
uninitialised stack data.

Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Export usb_serial_generic_write_start which is needed when implementing
a custom resume function while still relying on the generic write
implementation.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Add memory-flags parameter to usb_serial_generic_write_start which is
called from write, resume and completion handler, all with different
allocation requirements.

Note that by using the memory flag to determine when called from the
completion handler, everything will work as before even if the
completion handler is run with interrupts enabled (as suggested).
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Clean up some comments, drop excessive comments and fix-up style.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The DECLARE_BITMAP macro should be used for declaring this bitmap.
This commit converts the busmap from a struct to a simple (static)
bitmap, using the DECLARE_BITMAP macro from linux/types.h.

Please review, as I'm new to kernel development, I don't know if this
has any hidden side effects!

Suggested by joe@perches.com
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Currently, Samsung is using 'EXYNOS' as the name of Samsung SoCs.
Thus, ehci-exynos is preferred than ehci-s5p.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The non-DT for EXYNOS SoCs is not supported from v3.11.
Thus, there is no need to support non-DT for Exynos EHCI driver.

The 'include/linux/platform_data/usb-ehci-s5p.h' file has been
used for non-DT support. Thus, the 'usb-ehci-s5p.h' file can
be removed.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Since commit ca914350 "ARM: EXYNOS: Remove unused board files",
s5p_device_ehci is not used anymore. Thus, s5p_device_ehci can
be removed. Also, unnecessary S5P_DEV_USB_EHCI option is removed.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

For improved scheduling of transfers through a Transaction Translator,
ehci-hcd will need to store a bunch of information associated with the
FS/LS bus on the downstream side of the TT.  This patch adds a pointer
for such HCD-private data to the usb_tt structure.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch significantly changes the scheduling code in ehci-hcd.
Instead of calculating the current bandwidth utilization by trudging
through the schedule and adding up the times used by the existing
transfers, we will now maintain a table holding the time used for each
of 64 microframes.  This will drastically speed up the bandwidth
computations.

In addition, it eliminates a theoretical bug.  An isochronous endpoint
may have bandwidth reserved even at times when it has no transfers
listed in the schedule.  The table will keep track of the reserved
bandwidth, whereas adding up entries in the schedule would miss it.

As a corollary, we can keep bandwidth reserved for endpoints even
when they aren't in active use.  Eventually the bandwidth will be
reserved when a new alternate setting is installed; for now the
endpoint's reservation takes place when its first URB is submitted.

A drawback of this approach is that transfers with an interval larger
than 64 microframes will have to be charged for bandwidth as though
the interval was 64.  In practice this shouldn't matter much;
transfers with longer intervals tend to be rather short anyway (things
like hubs or HID devices).

Another minor drawback is that we will keep track of two different
period and phase values: the actual ones and the ones used for
bandwidth allocation (which are limited to 64).  This adds only a
small amount of overhead: 3 bytes for each endpoint.

The patch also adds a new debugfs file named "bandwidth" to display
the information stored in the new table.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

This patch begins the process of unifying the scheduling parameters
that ehci-hcd uses for interrupt and isochronous transfers.  It
creates an ehci_per_sched structure, which will be stored in both
ehci_qh and ehci_iso_stream structures, and will contain the common
scheduling information needed for both.

Initially we merely create the new structure and move some existing
fields into it.  Later patches will add more fields and utilize these
structures in improved scheduling algorithms.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ehci-hcd is inconsistent in the sentinel values it uses to indicate
that no frame number has been assigned for a periodic transfer.  Some
places it uses NO_FRAME (defined as 65535), other places it uses -1,
and elsewhere it uses 9999.

This patch defines a value for NO_FRAME which can fit in a 16-bit
signed integer, and changes the code to use it everywhere.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ehci-hcd uses a value of 0 in an endpoint's toggle flag to indicate
that the endpoint has been reset (and therefore the Data Toggle bit
needs to be cleared in the endpoint's QH overlay region).

The toggle flag should be set to 0 only when ehci_endpoint_reset()
succeeds.  This patch moves the usb_settoggle() call into the
appropriate branch of the "if" statement.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The scheduling code in ehci-hcd contains an error.  For full-speed
isochronous-OUT transfers, the EHCI spec forbids scheduling
Start-Split transactions in H-microframe 7, but the driver allows it
anyway.  This patch adds a check to prevent it.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Although the bandwidth statistics maintained by ehci-hcd show up only
in the /sys/kernel/debug/usb/devices file, they ought to be calculated
correctly.  The calculation for full-speed isochronous endpoints is
wrong; it mistakenly yields bytes per microframe instead of bytes per
frame.  The "interval" value, which is in frames, should not be
converted to microframes.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

The check_intr_schedule() routine in ehci-hcd looks at the wrong
microframes when checking to see if a full-speed or low-speed
interrupt endpoint will fit in the periodic schedule.  If the
Start-Split transaction is scheduled for microframe N then the
Complete-Split transactions get scheduled for microframes N+2, N+3, and
N+4.  However the code considers N+1, N+2, and N+3 instead.

This patch fixes the limits on the "for" loop and also improves the
use of whitespace.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Host controller drivers use the NS_TO_US macro to convert transaction
times, which are computed in nanoseconds, to microseconds for
scheduling.  Periodic scheduling requires worst-case estimates, but
the macro does its conversion using round-to-nearest.  This patch
changes it to use round-up, giving a correct worst-case value.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

usb_wait_anchor_empty_timeout() should wait till the completion handler
has run. Both the zd1211rw driver and the uas driver (in its task mgmt) depend
on the completion handler having completed when usb_wait_anchor_empty_timeout()
returns, as they read state set by the completion handler after an
usb_wait_anchor_empty_timeout() call.

But __usb_hcd_giveback_urb() calls usb_unanchor_urb before calling the
completion handler. This is necessary as the completion handler may
re-submit and re-anchor the urb. But this introduces a race where the state
these drivers want to read has not been set yet by the completion handler
(this race is easily triggered with the uas task mgmt code).

I've considered adding an anchor_count to struct urb, which would be
incremented on anchor and decremented on unanchor, and then only actually
do the anchor / unanchor on 0 -> 1 and 1 -> 0 transtions, combined with
moving the unanchor call in hcd_giveback_urb to after calling the completion
handler. But this will only work if urb's are only re-anchored to the same
anchor as they were anchored to before the completion handler ran.

And at least one driver re-anchors to another anchor from the completion
handler (rtlwifi).

So I have come up with this patch instead, which adds the ability to
suspend wakeups of usb_wait_anchor_empty_timeout() waiters to the usb_anchor
functionality, and uses this in __usb_hcd_giveback_urb() to delay wake-ups
until the completion handler has run.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

And do so in a way which ensures that any fields added in the future will
also get properly zero-ed.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

When devm_usb_get_phy() fails, usb_put_hcd() should be called
to prevent memory leak.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Allows MSM EHCI controller to be specified via device tree.
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Acked-by: David Brown <davidb@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Use struct usb_hcd::phy to hold USB PHY instance.
Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Acked-by: David Brown <davidb@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

These aren't necessary after switch and if blocks.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>