usb: gadget: renesas_usbhs: move done callback to struct usbhs_pkt
transfer done function was registered in struct struct usbhs_pipe_info.
It was good for mod_gadget, but not good for mod_host.
This function move it to struct usbhs_pkt.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
current mod_gadget had got usb speed on
usbhsg_irq_dev_state() which is status change interrupt callback function.
And the usb speed data was included in its parameter.
But this style works for mod_gadget,
but doesn't work for mod_host which
isn't interrupted when device status was changed.
This patch add usbhs_bus_get_speed() to solve this issue.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
usb: gadget: renesas_usbhs: change usbhsc_bus_ctrl() to usbsc_set_buswait()
renesas_usbhs will have register DVSTCTR control function for HOST support.
This patch changes usbhsc_bus_ctrl() to usbsc_set_buswait(),
to remove DVSTCTR access from it,
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
usb: gadget: renesas_usbhs: each pipe hold maxpacket size
Current renesas_usbhs pipe accessed DCPMAXP/PIPEMAXP register
to get own maxpacket size every time.
But maxpacket size isn't changed after pipe start,
and register access is too slow.
This patch adds new maxp variable to keep own maxpacket.
And un-used function are removed.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
usb: gadget: renesas_usbhs: remove desc from usbhs_pipe_malloc
Current usbhs_pipe_malloc() used usb_endpoint_descriptor to
get necessary information.
It was very good for mod_gadget which allocate pipe in runtime,
but is not good for mod_host which allocate pipe in initial timing.
This patch remove usb_endpoint_descriptor from usbhs_pipe_malloc()
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
Paul Zimmerman [Fri, 30 Sep 2011 22:26:06 +0000 (15:26 -0700)]
usb: gadget: storage: fix mass storage gadgets to work with Synopsys UDC
The Synopsys USB device controller requires all OUT transfer request
lengths to be aligned to max packet size. The mass storage gadgets do
not meet this requirement for Super Speed. The gadgets already have a
function which performs this alignment for CBW packets, so use it for
data packets too.
The alternative would be to implement bounce buffers in the DWC3
driver, but that could have a significant impact on performance.
This version is based upon a more-correct patch written by Alan
Stern.
Signed-off-by: Paul Zimmerman <paulz@synopsys.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
Daniel Mack [Wed, 28 Sep 2011 14:41:34 +0000 (16:41 +0200)]
USB: gadget: f_midi: allow a dynamic number of input and output ports
The code in the MIDI gadget was already sort of prepared for multi-port
configuration, so the streaming logic itself didn't need much tweaking.
However, the descriptors change when the number of ports do, and so some
rework of the the preparation algorithms were necessary.
Successfully tested on Linux and Max OS X hosts for both input and
output streams.
Signed-off-by: Daniel Mack <zonque@gmail.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Felipe Balbi <balbi@ti.com>
Daniel Mack [Wed, 28 Sep 2011 14:41:33 +0000 (16:41 +0200)]
USB: gadget: midi: refactor the device code
Make use of the newly added MIDI function in f_midi.c and strip down
the MIDI gadget code radically. Also use the generic framework function
to avoid code duplication and rename some symbols to bring them in sync
with other code in the gadget framework.
[ balbi@ti.com : fix Section mismatch warnings.
rebased on top of usb_speed_string() patch to
avoid conflicts. ]
Signed-off-by: Daniel Mack <zonque@gmail.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Felipe Balbi <balbi@ti.com>
Daniel Mack [Wed, 28 Sep 2011 14:41:32 +0000 (16:41 +0200)]
USB: gadget: midi: add midi function driver
This patch adds f_midi.c to implement a USB gadget function that works
with the composite framework, so it can be combined with other USB
functions.
The code for the ALSA/MIDI logic was taken from the midi device gadget,
other parts have been rewritten to benefit from the dynamic descriptor
allocation features.
This was successfully tested on an OMAP3 board.
Signed-off-by: Daniel Mack <zonque@gmail.com> Cc: Greg Kroah-Hartman <gregkh@suse.de> Signed-off-by: Felipe Balbi <balbi@ti.com>
Randy Dunlap [Fri, 7 Oct 2011 20:57:42 +0000 (13:57 -0700)]
usb gadget: fix langwell_udc.c build error
Move function to fix langwell_udc.c build error:
drivers/usb/gadget/langwell_udc.c: In function 'show_langwell_udc':
drivers/usb/gadget/langwell_udc.c:1693:3: error: implicit declaration of function 'lpm_device_speed'
drivers/usb/gadget/langwell_udc.c: At top level:
drivers/usb/gadget/langwell_udc.c:2637:37: error: conflicting types for 'lpm_device_speed'
drivers/usb/gadget/langwell_udc.c:1693:20: note: previous implicit declaration of 'lpm_device_speed' was here
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Acked-by: Felipe Balbi <balbi@ti.com>
Cc: linux-usb@vger.kernel.org
SH7757 has a USB function with internal DMA controller (SUDMAC).
This patch supports the SUDMAC. The SUDMAC is incompatible with
general-purpose DMAC. So, it doesn't use dmaengine.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
usb: gadget: r8a66597-udc: add function for external controller
R8A66597 has the pin of WR0 and WR1. So, if one write-pin of CPU
connects to the pins, we have to change the setting of FIFOSEL
register in the controller. If we don't change the setting,
the controller cannot send the data of odd length.
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Signed-off-by: Felipe Balbi <balbi@ti.com>
Some people think that this line is not compatible with the GPL. The
statement was required due to the Buenos Aires Convention and is now
deprecated. I remove it because it is said that it is pointless nowdays.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Use "ep0in" and "ep0out" instead "ep1in" and "ep0out" which is confusing
and not consistent with the remaining output.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb: dwc3: ep0: remove second giveback in error case
We already give requests back in dwc3_ep0_stall_and_restart() so
doing it again here will most likely corrupt the list.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Felipe Balbi [Fri, 30 Sep 2011 07:58:36 +0000 (10:58 +0300)]
usb: dwc3: ep0: Make USB30CV happy with SetAddress
According to USB 3.0 Specification, a SetAddress()
while device is in Configured State has an unspecified
behavior (see Section 9.4.6). Still USB30CV wasn't
happy with my Stall reply.
To make that thing happy, just accept the SetAddress()
always. No problems have been observed thus far.
Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
user namespace: usb: make usb urbs user namespace aware (v2)
Add to the dev_state and alloc_async structures the user namespace
corresponding to the uid and euid. Pass these to kill_pid_info_as_uid(),
which can then implement a proper, user-namespace-aware uid check.
Changelog:
Sep 20: Per Oleg's suggestion: Instead of caching and passing user namespace,
uid, and euid each separately, pass a struct cred.
Sep 26: Address Alan Stern's comments: don't define a struct cred at
usbdev_open(), and take and put a cred at async_completed() to
ensure it lasts for the duration of kill_pid_info_as_cred().
Dan Carpenter [Tue, 27 Sep 2011 06:25:19 +0000 (09:25 +0300)]
USB: message: cleanup min_t() cast in usb_sg_init()
"length" is type size_t so the cast to unsigned int truncates the
upper bytes. This isn't an issue in real life (I've checked the
callers) but it's a bit messy.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb/core/devio.c: Check for printer class specific request
In the usb printer class specific request get_device_id the value of
wIndex is (interface << 8 | altsetting) instead of just interface.
This enables the detection of some printers with libusb.
USB: pid_ns: ensure pid is not freed during kill_pid_info_as_uid
Alan Stern points out that after spin_unlock(&ps->lock) there is no
guarantee that ps->pid won't be freed. Since kill_pid_info_as_uid() is
called after the spin_unlock(), the pid passed to it must be pinned.
Alan Stern [Mon, 26 Sep 2011 15:25:26 +0000 (11:25 -0400)]
USB: UHCI: improve comments and logic for root-hub suspend
This patch (as1488) improves the comments and logic in uhci-hcd's
suspend routine. The existing comments are hard to understand and
don't give a good idea of what's really going on.
The question of whether EGSM (Enter Global Suspend Mode) and RD
(enable Resume Detect interrupts) can be useful when they're not both
set is difficult. The spec doesn't give any details on how they
interact with system wakeup, although clearly they are meant to be
used together. To be safe, the patch changes the subroutine so that
neither bit gets set unless they both do. There shouldn't be any
functional changes from this; only systems that are designed badly or
broken in some way need to avoid using those bits.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Alan Stern [Mon, 26 Sep 2011 15:23:38 +0000 (11:23 -0400)]
USB: Update USB default wakeup settings
This patch (as1486) implements the kernel's new wakeup policy for USB
host controllers. Since they don't generate wakeup requests on their
but merely forward requests from their root hubs toward the CPU, they
should be enabled for wakeup by default.
Also, to be compliant with both the old and new policies, root hubs
should not be enabled for remote wakeup by default. Userspace must
enable it explicitly if it is desired.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb/xhci: remove CONFIG_PCI in xhci.c's probe function
This removes the need of ifdefs within the init function and with it the
headache about the correct clean without bus X but with bus/platform Y &
Z.
xhci-pci is only compiled if CONFIG_PCI is selected which can be
de-selected now without trouble. For now the result is kinda useless
because we have no other glue code. However, since nobody is using
USB_ARCH_HAS_XHCI then it should not be an issue :)
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
xhci_gen_setup() is generic so it can be used to perform the bare xhci
setup even on non-pci based platform. The typedef for the function
pointer is moved into the headerfile
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
- xhci_gen_setup()
The major remaining of xhci_pci_setup() is now containing the generic
part of the xhci setup. It allocates the xhci struct, setup
hcs_params? and friends, performs xhci_halt(), xhci_init and so one.
It also obtains the quirks via a callback
- xhci_pci_quirks()
It checks the origin of the xhci core and sets core specific quirks.
- xhci_pci_setup()
PCI specific setup functions. Besides calling xhci_gen_setup() with
xhci_pci_quirks() as an argument it performs PCI specific setup like
obtaining the address of sbrn via a PCI config space.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb/xhci: replace pci_*_consistent() with dma_*_coherent()
pci_*_consistent() calls dma_*_coherent() with GFP_ATOMIC and requires
pci_dev struct. This is a preparion for later where we no longer have
the pci struct around.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The MSI related fuctionality requires a few structs which are not
available if CONFIG_PCI is not enabled. This is a prepartion to allow
xhci be built without CONFIG_PCI set.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb/xhci: group MSI interrupt registration into its own function
This patch moves the complete MSI/MSI-X/Legacy dance into its own
function. There is however one difference: If the XHCI_BROKEN_MSI flag
is set then we don't free and register the irq, we simply return.
This is preparation for later PCI decouple.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Felipe Balbi [Fri, 23 Sep 2011 21:19:56 +0000 (14:19 -0700)]
usb/host: introduce USB_ARCH_HAS_XHCI
to make it look like OHCI and EHCI, we introduce
that symbol and USB_XHCI_HCD depend on that
instead of PCI.
[bigeasy@linutronix.de: wire up USB_ARCH_HAS_HCD]
Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Setting the chain (CH) bit in the link TRB of isochronous transfer rings
is required by AMD 0.96 xHCI host controller to successfully transverse
multi-TRB TD that span through different memory segments.
When a Missed Service Error event occurs, if the chain bit is not set in
the link TRB and the host skips TDs which just across a link TRB, the
host may falsely recognize the link TRB as a normal TRB. You can see
this may cause big trouble - the host does not jump to the right address
which is pointed by the link TRB, but continue fetching the memory which
is after the link TRB address, which may not even belong to the host,
and the result cannot be predicted.
This causes some big problems. Without the former patch I sent: "xHCI:
prevent infinite loop when processing MSE event", the system may hang.
With that patch applied, system does not hang, but the host still access
wrong memory address and isoc transfer will fail. With this patch,
isochronous transfer works as expected.
This patch should be applied to kernels as old as 2.6.36, which was when
the first isochronous support was added for the xHCI host controller.
If the device pass the USB2 software LPM and the host supports hardware
LPM, enable hardware LPM for the device to let the host decide when to
put the link into lower power state.
If hardware LPM is enabled for a port and driver wants to put it into
suspend, it must first disable hardware LPM, resume the port into U0,
and then suspend the port.
This patch tests USB2 software LPM for a USB2 LPM-capable device.
When a lpm-capable device is addressed, if the host also supports software
LPM, apply a test by putting the device into L1 state and resume it to see
if the device can do L1 suspend/resume successfully.
If the device fails to enter L1 or resume from L1 state, it may not
function normally and usbcore may disconnect and re-enumerate it. In this
case, store the device's Vid and Pid information, make sure the host will
not test LPM for it twice.
The test result is per device/host. Some devices claim to be lpm-capable,
but fail to enter L1 or resume. So the test is necessary.
The xHCI 1.0 errata has modified the USB2.0 LPM implementation. It redefines
the HIRD field to BESL, and adds another register Port Hardware LPM Control
(PORTHLPMC). However, this should not affect the LPM behavior on xHC which
does not implement 1.0 errata.
USB2.0 LPM errata defines a new bit BESL in the device's USB 2.0 extension
descriptor. If the device reports it uses BESL, driver should use BESL
instead of HIRD for it.
When the link state changes, xHC will report a port status change event
and set the PORT_PLC bit, for both USB3 and USB2 root hub ports.
The PLC will be cleared by usbcore for USB3 root hub ports, but not for
USB2 ports, because they do not report USB_PORT_STAT_C_LINK_STATE in
wPortChange.
Clear it for USB2 root hub ports in handle_port_status().
This commit gets BOS(Binary Device Object Store) descriptor set for Super
Speed devices and High Speed devices which support BOS descriptor.
BOS descriptor is used to report additional USB device-level capabilities
that are not reported via the Device descriptor. By getting BOS descriptor
set, driver can check device's device-level capability such as LPM
capability.
Eric Benoit [Sat, 24 Sep 2011 06:04:50 +0000 (02:04 -0400)]
USB: pl2303: add id for SMART device
Add vendor and product ID for the SMART USB to serial adapter. These
were meant to be used with their SMART Board whiteboards, but can be
re-purposed for other tasks. Tested and working (at at least 9600 bps).
Kautuk Consul [Mon, 19 Sep 2011 23:53:12 +0000 (16:53 -0700)]
xhci-mem.c: Check for ring->first_seg != NULL
There are 2 situations wherein the xhci_ring* might not get freed:
- When xhci_ring_alloc() -> xhci_segment_alloc() returns NULL and
we goto the fail: label in xhci_ring_alloc. In this case, the ring
will not get kfreed.
- When the num_segs argument to xhci_ring_alloc is passed as 0 and
we try to free the rung after that.
( This doesn't really happen as of now in the code but we seem to
be entertaining num_segs=0 in xhci_ring_alloc )
This should be backported to kernels as old as 2.6.31.
Signed-off-by: Kautuk Consul <consul.kautuk@gmail.com> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Sarah Sharp [Wed, 14 Sep 2011 21:24:52 +0000 (14:24 -0700)]
USB: When hot reset for USB3 fails, try warm reset.
When a hot reset (standard USB port reset) fails on a USB 3.0 port, the
host controller transitions to the "Error" state. It reports the port
link state as "Inactive", sets the link state change flag, and (if the
device disconnects) also reports the disconnect and connect change status.
It's also supposed to transition the link state to "RxDetect", but the NEC
µPD720200 xHCI host does not.
Unfortunately, Harald found that the combination of the NEC µPD720200 and
a LogiLink USB 3.0 to SATA adapter triggered this issue. The USB core
would reset the device, the port would go into this error state, and the
device would never be enumerated. This combination works under Windows,
but not under Linux.
When a hot reset fails on a USB 3.0 port, and the link state is reported
as Inactive, fall back to a warm port reset instead. Harald confirms that
with a warm port reset (along with all the change bits being correctly
cleared), the USB 3.0 device will successfully enumerate.
Harald also had to add two other patches ("xhci: Set change bit when warm
reset change is set." and "usbcore: refine warm reset logic") to make this
setup work. Since the warm reset refinement patch is not destined for the
stable kernels (it's too big), this patch should not be backported either.
This fixes https://bugzilla.kernel.org/show_bug.cgi?id=41752
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Tested-by: Harald Brennich <harald.brennich@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Sarah Sharp [Tue, 13 Sep 2011 23:41:13 +0000 (16:41 -0700)]
xhci: USB 3.0 BW checking.
The Intel Panther Point xHCI host tracks SuperSpeed endpoints in a
different way than USB 2.0/1.1 endpoints. The bandwidth interval tables
are not used, and instead the bandwidth is calculated in a very simple
way. Bandwidth for SuperSpeed endpoints is tracked individually in each
direction, since each direction has the full USB 3.0 bandwidth available.
10% of the bus bandwidth is reserved for non-periodic transfers.
This checking would be more complex if we had USB 3.0 LPM enabled, because
an additional latency for isochronous ping times need to be taken into
account. However, we don't have USB 3.0 LPM support in Linux yet.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Sarah Sharp [Tue, 13 Sep 2011 23:41:12 +0000 (16:41 -0700)]
xhci: Fix mult base in endpoint bandwidth info.
The "Mult" bits in the SuperSpeed Endpoint Companion Descriptor are
zero-based, and the xHCI host controller wants them to be zero-based in
the input context. However, for the bandwidth math, we want them to be
one-based. Fix this.
Fix the documentation about the endpoint bandwidth mult variable in the
xhci.h file, which says it is zero-based. Also fix the documentation
about num_packets, which is also one-based, not zero-based.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Current waiting time for warm(BH) reset in hub_port_warm_reset() is too short
for xHC host to complete the warm reset and report a BH reset change.
This patch increases the waiting time for warm reset and merges the function
into hub_port_reset(), so it can handle both cold reset and warm reset, and
factor out hub_port_finish_reset() to make the code looks cleaner.
This fixes the issue that driver fails to clear BH reset change and port is
"dead".
Signed-off-by: Andiry Xu <andiry.xu@amd.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
usb/xhci: ignore xhci version while checking for the link quirk
instead of reading the xhci interface version each time _even_ if the
quirk is not required, simply check if the quirk flag is set. This flag
is only set of the module parameter is set and here is where I moved the
version check to.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
After auto-delink command is triggered, the CSW won't be sent back
to host side, in which scenario, the USB Mass Storage driver will
wait for the completion of the URB for MAX_SCHEDULE_TIMEOUT.
Oliver Neukum [Tue, 13 Sep 2011 06:42:21 +0000 (08:42 +0200)]
USB: add RESET_RESUME for webcams shown to be quirky
The new runtime PM code has shown that many webcams suffer
from a race condition that may crash them upon resume.
Runtime PM is especially prone to show the problem because
it retains power to the cameras at all times. However
system suspension may also crash the devices and retain
power to the devices.
The only way to solve this problem without races is in
usbcore with the RESET_RESUME quirk.
This patch (as1484) adds documentation for ehci-hcd's "companion"
sysfs attribute, which was added to the kernel over four years ago but
never documented.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Ming Lei [Mon, 5 Sep 2011 13:05:58 +0000 (21:05 +0800)]
usb: ehci: remove the 1st wmb in qh_append_tds
According to ehci spec 4.10.2, Advance Queue
If the fetched qTD has its Active bit set to a zero, the
host controller aborts the queue advance and follows the
queue head's horizontal pointer to the next schedule data
structure.
the 'qtd' will be linked into qh hardware queue after the line
below
*dummy = *qtd;
is executed and observed by EHCI HC, but EHCI HC won't have chance to
fetch the qtd descriptor pointed by 'qtd' in qh_append_tds until the
line below
dummy->hw_token = token; #set Active bit here
is executed by CPU and observed by EHCI HC.
There is already one 'wmb' to order writing to 'dummy'/'qtd' descriptors
and writing 'token' to 'dummy' descriptor(set Active bit), so the 1st
wmb is not needed and can be removed.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
projects / linux-beck.git / log