usb: gadget: Use u16 types for 16-bit fields

Since the beginning of time, struct usb_ep::maxpacket was a bitfield,
and when new 16-bit members were added, the convention was followed:

1da177e4c3f41

usb: gadget: Use u16 types for 16-bit fields

Since the beginning of time, struct usb_ep::maxpacket was a bitfield,
and when new 16-bit members were added, the convention was followed:

1da177e4c3f41 (Linus Torvalds 2005-04-16 236) unsigned maxpacket:16;
e117e742d3106 (Robert Baldyga 2013-12-13 237) unsigned maxpacket_limit:16;
a59d6b91cbca5 (Tatyana Brokhman 2011-06-28 238) unsigned max_streams:16;

However, there is no need for this as a simple u16 can be used instead,
simplifying the struct and the resulting compiler binary output. Switch
to u16 for all three, and rearrange struct slightly to minimize holes.
No change in the final size of the struct results; the 2 byte gap is
just moved to the end, as seen with pahole:

- /* XXX 2 bytes hole, try to pack */
...
/* size: 72, cachelines: 2, members: 15 */
...
+ /* padding: 2 */

Changing this simplifies future introspection[1] of maxpacket's type during
allocations:

drivers/usb/gadget/function/f_tcm.c:330:24: error: 'typeof' applied to a bit-field
330 | fu->cmd.buf = kmalloc(fu->ep_out->maxpacket, GFP_KERNEL);

Link: https://lore.kernel.org/all/[email protected] [1]
Signed-off-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: Support already-mapped DMA SGs

Add a new 'sg_was_mapped' field to the struct usb_request. This field
can be used to indicate that the scatterlist associated to the USB
transfer has alre

usb: gadget: Support already-mapped DMA SGs

Add a new 'sg_was_mapped' field to the struct usb_request. This field
can be used to indicate that the scatterlist associated to the USB
transfer has already been mapped into the DMA space, and it does not
have to be done internally.

Signed-off-by: Paul Cercueil <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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Revert "usb: dwc3: Support EBC feature of DWC_usb31"

This reverts commit 398aa9a7e77cf23c2a6f882ddd3dcd96f21771dc.

The update to the gadget API to support EBC feature is incomplete. It's
missing at

Revert "usb: dwc3: Support EBC feature of DWC_usb31"

This reverts commit 398aa9a7e77cf23c2a6f882ddd3dcd96f21771dc.

The update to the gadget API to support EBC feature is incomplete. It's
missing at least the following:
* New usage documentation
* Gadget capability check
* Condition for the user to check how many and which endpoints can be
used as "fifo_mode"
* Description of how it can affect completed request (e.g. dwc3 won't
update TRB on completion -- ie. how it can affect request's actual
length report)

Let's revert this until it's ready.

Fixes: 398aa9a7e77c ("usb: dwc3: Support EBC feature of DWC_usb31")
Signed-off-by: Thinh Nguyen <[email protected]>
Link: https://lore.kernel.org/r/3042f847ff904b4dd4e4cf66a1b9df470e63439e.1707441690.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: dwc3: Support EBC feature of DWC_usb31

Support configuration and use of bulk endpoints in the so-called EBC
mode described in the DBC_usb31 databook (appendix E)

Added a bit fifo_mode to usb_e

usb: dwc3: Support EBC feature of DWC_usb31

Support configuration and use of bulk endpoints in the so-called EBC
mode described in the DBC_usb31 databook (appendix E)

Added a bit fifo_mode to usb_ep to indicate to the UDC driver that a
specific endpoint is to operate in the EBC (or equivalent) mode when
enabled

Added macros for bits 15 and 14 of DEPCFG parameter 1 to indicate EBC
mode and write back behaviour. These bits will be set to 1 when
configuring an EBC endpoint as described in the programming guide

Signed-off-by: Manan Aurora <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: clarify usage of USB_GADGET_DELAYED_STATUS

USB_GADGET_DELAYED_STATUS was introduced in commit 1b9ba000177e ("usb:
gadget: composite: Allow function drivers to pause control transfers").

usb: gadget: clarify usage of USB_GADGET_DELAYED_STATUS

USB_GADGET_DELAYED_STATUS was introduced in commit 1b9ba000177e ("usb:
gadget: composite: Allow function drivers to pause control transfers").
It was initially intended for the composite framework to allow delaying
completing the status stage of a SET_CONFIGURATION request until all
functions are ready.

Unfortunately, that commit had an unintended side-effect of returning
USB_GADGET_DELAYED_STATUS from the ->setup() call of the composite
framework gadget driver.

As a result of this and the incomplete documentation, some UDC drivers
started relying on USB_GADGET_DELAYED_STATUS to decide when to avoid
autocompleting the status stage for 0-length control transfers. dwc3 was
the first in commit 5bdb1dcc6330 ("usb: dwc3: ep0: handle delayed_status
again"). And a number of other UDC drivers followed later, probably
relying on the dwc3 behavior as a reference.

Unfortunately, this violated the interface between the UDC and the
gadget driver for 0-length control transfers: the UDC driver must only
proceed with the status stage for a 0-length control transfer once the
gadget driver queued a response to EP0.

As a result, a few gadget drivers are partially broken when used with
a UDC that only delays the status stage for 0-length transfers when
USB_GADGET_DELAYED_STATUS is returned from the setup() callback.

This includes Raw Gadget and GadgetFS. For FunctionFS, a workaround was
added in commit 946ef68ad4e4 ("usb: gadget: ffs: Let setup() return
USB_GADGET_DELAYED_STATUS") and commit 4d644abf2569 ("usb: gadget: f_fs:
Only return delayed status when len is 0").

The proper solution to this issue would be to contain
USB_GADGET_DELAYED_STATUS within the composite framework and make all
UDC drivers to not complete the status stage for 0-length requests on
their own.

Unfortunately, there is quite a few UDC drivers that need to get fixed
and the required changes for some of them are not trivial.

For now, update the comments to clarify that USB_GADGET_DELAYED_STATUS
must not be used by the UDC drivers.

The following two commits also add workarounds to Raw Gadget and GadgetFS
to make them compatible with the broken UDC drivers until they are fixed.

Acked-by: Alan Stern <[email protected]>
Signed-off-by: Andrey Konovalov <[email protected]>
Link: https://lore.kernel.org/r/7f0ee06c68c7241c844cd50f8565fdd5ead79b1b.1693237258.git.andreyknvl@gmail.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: Add function wakeup support

USB3.2 spec section 9.2.5.4 quotes that a function may signal that
it wants to exit from Function Suspend by sending a Function
Wake Notification to the host

usb: gadget: Add function wakeup support

USB3.2 spec section 9.2.5.4 quotes that a function may signal that
it wants to exit from Function Suspend by sending a Function
Wake Notification to the host if it is enabled for function
remote wakeup. Add an api in composite layer that can be used
by the function drivers to support this feature. Also expose
a gadget op so that composite layer can trigger a wakeup request
to the UDC driver.

Reviewed-by: Thinh Nguyen <[email protected]>
Signed-off-by: Elson Roy Serrao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: Properly configure the device for remote wakeup

The wakeup bit in the bmAttributes field indicates whether the device
is configured for remote wakeup. But this field should be allowed t

usb: gadget: Properly configure the device for remote wakeup

The wakeup bit in the bmAttributes field indicates whether the device
is configured for remote wakeup. But this field should be allowed to
set only if the UDC supports such wakeup mechanism. So configure this
field based on UDC capability. Also inform the UDC whether the device
is configured for remote wakeup by implementing a gadget op.

Reviewed-by: Thinh Nguyen <[email protected]>
Signed-off-by: Elson Roy Serrao <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: configfs: Support arbitrary string descriptors

Add a framework to allow users to define arbitrary string descriptors
for a USB Gadget. This is modelled as a new type of config item rath

usb: gadget: configfs: Support arbitrary string descriptors

Add a framework to allow users to define arbitrary string descriptors
for a USB Gadget. This is modelled as a new type of config item rather
than as hardcoded attributes so as to be as flexible as possible.

Signed-off-by: Daniel Scally <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: Follow-up to SPDX identifiers addition - remove now useless comments

All these files have been updated in the commit given in the Fixes: tag
below.

When the SPDX-License-Identifier: has been a

USB: Follow-up to SPDX identifiers addition - remove now useless comments

All these files have been updated in the commit given in the Fixes: tag
below.

When the SPDX-License-Identifier: has been added, the corresponding text at
the beginning of the files has not been deleted.
All these texts are about GPL-2.0, with different variation in the wording.

Remove these now useless lines to save some LoC.

Fixes: 5fd54ace4721 ("USB: add SPDX identifiers to all remaining files in drivers/usb/")
Signed-off-by: Christophe JAILLET <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: gadget: Add ID numbers to gadget names

Putting USB gadgets on a new bus of their own encounters a problem
when multiple gadgets are present: They all have the same name! The
driver core fails

USB: gadget: Add ID numbers to gadget names

Putting USB gadgets on a new bus of their own encounters a problem
when multiple gadgets are present: They all have the same name! The
driver core fails with a "sys: cannot create duplicate filename" error
when creating any of the /sys/bus/gadget/devices/<gadget-name>
symbolic links after the first.

This patch fixes the problem by adding a ".N" suffix to each gadget's
name when the gadget is registered (where N is a unique ID number),
thus making the names distinct.

Reported-and-tested-by: Geert Uytterhoeven <[email protected]>
Signed-off-by: Alan Stern <[email protected]>
Reviewed-by: Geert Uytterhoeven <[email protected]>
Fixes: fc274c1e9973 ("USB: gadget: Add a new bus for gadgets")
Link: https://lore.kernel.org/r/YnqKAXKyp9Vq/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: gadget: Add a new bus for gadgets

This patch adds a "gadget" bus and uses it for registering gadgets and
their drivers. From now on, bindings will be managed by the driver
core rather than thr

USB: gadget: Add a new bus for gadgets

This patch adds a "gadget" bus and uses it for registering gadgets and
their drivers. From now on, bindings will be managed by the driver
core rather than through ad-hoc manipulations in the UDC core.

As part of this change, the driver_pending_list is removed. The UDC
core won't need to keep track of unbound drivers for later binding,
because the driver core handles all of that for us.

However, we do need one new feature: a way to prevent gadget drivers
from being bound to more than one gadget at a time. The existing code
does this automatically, but the driver core doesn't -- it's perfectly
happy to bind a single driver to all the matching devices on the bus.
The patch adds a new bitflag to the usb_gadget_driver structure for
this purpose.

A nice side effect of this change is a reduction in the total lines of
code, since now the driver core will do part of the work that the UDC
used to do.

A possible future patch could add udc devices to the gadget bus, say
as a separate device type.

Signed-off-by: Alan Stern <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: gadget: Rename usb_gadget_probe_driver()

In preparation for adding a "gadget" bus, this patch renames
usb_gadget_probe_driver() to usb_gadget_register_driver(). The new
name will be more accur

USB: gadget: Rename usb_gadget_probe_driver()

In preparation for adding a "gadget" bus, this patch renames
usb_gadget_probe_driver() to usb_gadget_register_driver(). The new
name will be more accurate, since gadget drivers will be registered on
the gadget bus and the probing will be done by the driver core, not
the UDC core.

Signed-off-by: Alan Stern <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: remove unnecessary AND operation when get ep maxp

usb_endpoint_maxp() already returns actual max packet size, no need
to AND 0x7ff.

Acked-by: Felipe Balbi <[email protected]>
Signed-off

usb: gadget: remove unnecessary AND operation when get ep maxp

usb_endpoint_maxp() already returns actual max packet size, no need
to AND 0x7ff.

Acked-by: Felipe Balbi <[email protected]>
Signed-off-by: Chunfeng Yun <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: udc: core: Introduce check_config to verify USB configuration

Some UDCs may have constraints on how many high bandwidth endpoints it can
support in a certain configuration. This API al

usb: gadget: udc: core: Introduce check_config to verify USB configuration

Some UDCs may have constraints on how many high bandwidth endpoints it can
support in a certain configuration. This API allows for the composite
driver to pass down the total number of endpoints to the UDC so it can verify
it has the required resources to support the configuration.

Signed-off-by: Wesley Cheng <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: UDC core: Add udc_async_callbacks gadget op

The Gadget API has a theoretical race when a gadget driver is unbound.
Although the pull-up is turned off before the driver's ->unbind
callback runs,

USB: UDC core: Add udc_async_callbacks gadget op

The Gadget API has a theoretical race when a gadget driver is unbound.
Although the pull-up is turned off before the driver's ->unbind
callback runs, if the USB cable were to be unplugged at just the wrong
moment there would be nothing to prevent the UDC driver from invoking
the ->disconnect callback after the unbind has finished. In theory,
other asynchronous callbacks could also happen during the time before
the UDC driver's udc_stop routine is called, and the gadget driver
would not be prepared to handle any of them.

We need a way to tell UDC drivers to stop issuing asynchronous (that is,
->suspend, ->resume, ->disconnect, ->reset, or ->setup) callbacks at
some point after the pull-up has been turned off and before the
->unbind callback runs. This patch adds a new ->udc_async_callbacks
callback to the usb_gadget_ops structure for precisely this purpose,
and it adds the corresponding support to the UDC core.

Later patches in this series add support for udc_async_callbacks to
several UDC drivers.

Acked-by: Felipe Balbi <[email protected]>
Signed-off-by: Alan Stern <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: fix spelling mistakes in header files

Fix some spelling mistakes in comments:
trasfer ==> transfer
consumtion ==> consumption
endoint ==> endpoint
sharable ==> shareable
contraints ==> constrai

usb: fix spelling mistakes in header files

Fix some spelling mistakes in comments:
trasfer ==> transfer
consumtion ==> consumption
endoint ==> endpoint
sharable ==> shareable
contraints ==> constraints
Auxilary ==> Auxiliary
correspondig ==> corresponding
interupt ==> interrupt
inifinite ==> infinite
assignement ==> assignment

Signed-off-by: Zhen Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: Introduce udc_set_ssp_rate() for SSP

A SuperSpeed Plus device may operate at different speed and lane count
(i.e. gen2x2, gen1x2, or gen2x1). Introduce gadget ops
udc_set_ssp_rate() to

usb: gadget: Introduce udc_set_ssp_rate() for SSP

A SuperSpeed Plus device may operate at different speed and lane count
(i.e. gen2x2, gen1x2, or gen2x1). Introduce gadget ops
udc_set_ssp_rate() to set the desire corresponding usb_ssp_rate for
SuperSpeed Plus capable devices.

If the USB device supports different speeds at SuperSpeed Plus, set the
device to operate with the maximum number of lanes and speed.

Signed-off-by: Thinh Nguyen <[email protected]>
Link: https://lore.kernel.org/r/9b85357cdadc02e3f0d653fd05f89eb46af836e1.1610592135.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: Introduce SSP rates and lanes

A USB device controller operating in SuperSpeed Plus may support gen2x1,
gen1x2, and/or gen2x2. Introduce SuperSpeed Plus signaling rate
generation and lan

usb: gadget: Introduce SSP rates and lanes

A USB device controller operating in SuperSpeed Plus may support gen2x1,
gen1x2, and/or gen2x2. Introduce SuperSpeed Plus signaling rate
generation and lane count to usb_gadget with the fields ssp_rate and
max_ssp_rate. The gadget driver can use these to setup the device BOS
descriptor and select the desire operating speed and number of lanes.

Signed-off-by: Thinh Nguyen <[email protected]>
Link: https://lore.kernel.org/r/b6d2196dcc3c73747f91abf9a082b20bbe276cc4.1610592135.git.Thinh.Nguyen@synopsys.com
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: UDC: Expand device model API interface

The routines used by the UDC core to interface with the kernel's
device model, namely usb_add_gadget_udc(),
usb_add_gadget_udc_release(), and usb_del_gadg

USB: UDC: Expand device model API interface

The routines used by the UDC core to interface with the kernel's
device model, namely usb_add_gadget_udc(),
usb_add_gadget_udc_release(), and usb_del_gadget_udc(), provide access
to only a subset of the device model's full API. They include
functionality equivalent to device_register() and device_unregister()
for gadgets, but they omit device_initialize(), device_add(),
device_del(), get_device(), and put_device().

This patch expands the UDC API by adding usb_initialize_gadget(),
usb_add_gadget(), usb_del_gadget(), usb_get_gadget(), and
usb_put_gadget() to fill in the gap. It rewrites the existing
routines to call the new ones.

CC: Anton Vasilyev <[email protected]>
CC: Evgeny Novikov <[email protected]>
CC: Benjamin Herrenschmidt <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Alan Stern <[email protected]>
Signed-off-by: Peter Chen <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>

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usb: linux/usb/gadget.h: fix duplicated word in comment

Change the doubled word "in" to "be in" in a comment.

Signed-off-by: Randy Dunlap <[email protected]>
Cc: Greg Kroah-Hartman <gregkh@linu

usb: linux/usb/gadget.h: fix duplicated word in comment

Change the doubled word "in" to "be in" in a comment.

Signed-off-by: Randy Dunlap <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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USB: Fix up terminology in include files

USB is a HOST/DEVICE protocol, as per the specification and all
documentation. Fix up terms that are not applicable to make things
match up with the terms u

USB: Fix up terminology in include files

USB is a HOST/DEVICE protocol, as per the specification and all
documentation. Fix up terms that are not applicable to make things
match up with the terms used through the rest of the USB stack.

Acked-by: Felipe Balbi <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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usb: gadget: core: sync interrupt before unbind the udc

The threaded interrupt handler may still be called after the
usb_gadget_disconnect is called, it causes the structures used
at interrupt handl

usb: gadget: core: sync interrupt before unbind the udc

The threaded interrupt handler may still be called after the
usb_gadget_disconnect is called, it causes the structures used
at interrupt handler was freed before it uses, eg the
usb_request. This issue usually occurs we remove the udc function
during the transfer. Below is the example when doing stress
test for android switch function, the EP0's request is freed
by .unbind (configfs_composite_unbind -> composite_dev_cleanup),
but the threaded handler accesses this request during handling
setup packet request.

In fact, there is no protection between unbind the udc
and udc interrupt handling, so we have to avoid the interrupt
handler is occurred or scheduled during the .unbind flow.

init: Sending signal 9 to service 'adbd' (pid 18077) process group...
android_work: did not send uevent (0 0 000000007bec2039)
libprocessgroup: Successfully killed process cgroup uid 0 pid 18077 in 6ms
init: Service 'adbd' (pid 18077) received signal 9
init: Sending signal 9 to service 'adbd' (pid 18077) process group...
libprocessgroup: Successfully killed process cgroup uid 0 pid 18077 in 0ms
init: processing action (init.svc.adbd=stopped) from (/init.usb.configfs.rc:14)
init: Received control message 'start' for 'adbd' from pid: 399 (/vendor/bin/hw/android.hardware.usb@1.

init: starting service 'adbd'...
read descriptors
read strings
Unable to handle kernel read from unreadable memory at virtual address 000000000000002a
android_work: sent uevent USB_STATE=CONNECTED
Mem abort info:
ESR = 0x96000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000004
CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=00000000e97f1000
using random self ethernet address
[000000000000002a] pgd=0000000000000000
Internal error: Oops: 96000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 232 Comm: irq/68-5b110000 Not tainted 5.4.24-06075-g94a6b52b5815 #92
Hardware name: Freescale i.MX8QXP MEK (DT)
pstate: 00400085 (nzcv daIf +PAN -UAO)
using random host ethernet address
pc : composite_setup+0x5c/0x1730
lr : android_setup+0xc0/0x148
sp : ffff80001349bba0
x29: ffff80001349bba0 x28: ffff00083a50da00
x27: ffff8000124e6000 x26: ffff800010177950
x25: 0000000000000040 x24: ffff000834e18010
x23: 0000000000000000 x22: 0000000000000000
x21: ffff00083a50da00 x20: ffff00082e75ec40
x19: 0000000000000000 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000
x15: 0000000000000000 x14: 0000000000000000
x13: 0000000000000000 x12: 0000000000000001
x11: ffff80001180fb58 x10: 0000000000000040
x9 : ffff8000120fc980 x8 : 0000000000000000
x7 : ffff00083f98df50 x6 : 0000000000000100
x5 : 00000307e8978431 x4 : ffff800011386788
x3 : 0000000000000000 x2 : ffff800012342000
x1 : 0000000000000000 x0 : ffff800010c6d3a0
Call trace:
composite_setup+0x5c/0x1730
android_setup+0xc0/0x148
cdns3_ep0_delegate_req+0x64/0x90
cdns3_check_ep0_interrupt_proceed+0x384/0x738
cdns3_device_thread_irq_handler+0x124/0x6e0
cdns3_thread_irq+0x94/0xa0
irq_thread_fn+0x30/0xa0
irq_thread+0x150/0x248
kthread+0xfc/0x128
ret_from_fork+0x10/0x18
Code: 910e8000 f9400693 12001ed7 79400f79 (3940aa61)
---[ end trace c685db37f8773fba ]---
Kernel panic - not syncing: Fatal exception
SMP: stopping secondary CPUs
Kernel Offset: disabled
CPU features: 0x0002,20002008
Memory Limit: none
Rebooting in 5 seconds..

Reviewed-by: Jun Li <[email protected]>
Signed-off-by: Peter Chen <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>

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usb: gadget: Introduce usb_request->is_last

To take advantage of DWC3 internal TRB prefetch and cache for
performance, inform the controller the last request with stream_id
before switching to a dif

usb: gadget: Introduce usb_request->is_last

To take advantage of DWC3 internal TRB prefetch and cache for
performance, inform the controller the last request with stream_id
before switching to a different stream transfer. This allows the
controller to maintain its transfer burst within the stream ID.

Introduce the usb-request is_last field to help inform the DWC3
controller of this.

Signed-off-by: Thinh Nguyen <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>

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usb: gadget: add "usb_validate_langid" function

The USB LANGID validation code in "check_user_usb_string" function is
moved to "usb_validate_langid" function which can be used by other usb
gadget dr

usb: gadget: add "usb_validate_langid" function

The USB LANGID validation code in "check_user_usb_string" function is
moved to "usb_validate_langid" function which can be used by other usb
gadget drivers.

Signed-off-by: Tao Ren <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>

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USB: Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
varia

USB: Replace zero-length array with flexible-array member

The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
int stuff;
struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <[email protected]>
Link: https://lore.kernel.org/r/20200220132017.GA29262@embeddedor
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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