<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/linux.git/drivers/usb/core/hcd.c, branch v6.6.132</title>
<subtitle>Linux kernel stable tree (mirror)</subtitle>
<id>https://git.radix-linux.su/kernel/linux.git/atom?h=v6.6.132</id>
<link rel='self' href='https://git.radix-linux.su/kernel/linux.git/atom?h=v6.6.132'/>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/'/>
<updated>2025-08-28T14:28:46+00:00</updated>
<entry>
<title>usb: core: hcd: fix accessing unmapped memory in SINGLE_STEP_SET_FEATURE test</title>
<updated>2025-08-28T14:28:46+00:00</updated>
<author>
<name>Xu Yang</name>
<email>xu.yang_2@nxp.com</email>
</author>
<published>2025-08-06T08:39:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=3b4a57b5cc3bae1904f479655f2949234e165796'/>
<id>urn:sha1:3b4a57b5cc3bae1904f479655f2949234e165796</id>
<content type='text'>
commit 8fe06185e11ae753414aa6117f0e798aa77567ff upstream.

The USB core will unmap urb-&gt;transfer_dma after SETUP stage completes.
Then the USB controller will access unmapped memory when it received
device descriptor. If iommu is equipped, the entire test can't be
completed due to the memory accessing is blocked.

Fix it by calling map_urb_for_dma() again for IN stage. To reduce
redundant map for urb-&gt;transfer_buffer, this will also set
URB_NO_TRANSFER_DMA_MAP flag before first map_urb_for_dma() to skip
dma map for urb-&gt;transfer_buffer and clear URB_NO_TRANSFER_DMA_MAP
flag before second map_urb_for_dma().

Fixes: 216e0e563d81 ("usb: core: hcd: use map_urb_for_dma for single step set feature urb")
Cc: stable &lt;stable@kernel.org&gt;
Reviewed-by: Jun Li &lt;jun.li@nxp.com&gt;
Signed-off-by: Xu Yang &lt;xu.yang_2@nxp.com&gt;
Acked-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Link: https://lore.kernel.org/r/20250806083955.3325299-1-xu.yang_2@nxp.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>USB: Remove remnants of Wireless USB and UWB</title>
<updated>2023-08-09T12:17:06+00:00</updated>
<author>
<name>Alan Stern</name>
<email>stern@rowland.harvard.edu</email>
</author>
<published>2023-08-09T00:44:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=1e4c574225cc5a0553115e5eb5787d1474db5b0f'/>
<id>urn:sha1:1e4c574225cc5a0553115e5eb5787d1474db5b0f</id>
<content type='text'>
Wireless USB has long been defunct, and kernel support for it was
removed in 2020 by commit caa6772db4c1 ("Staging: remove wusbcore and
UWB from the kernel tree.").

Nevertheless, some vestiges of the old implementation still clutter up
the USB subsystem and one or two other places.  Let's get rid of them
once and for all.

The only parts still left are the user-facing APIs in
include/uapi/linux/usb/ch9.h.  (There are also a couple of misleading
instances, such as the Sierra Wireless USB modem, which is a USB modem
made by Sierra Wireless.)

Signed-off-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Link: https://lore.kernel.org/r/b4f2710f-a2de-4fb0-b50f-76776f3a961b@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>USB: core: Change usb_get_device_descriptor() API</title>
<updated>2023-08-08T08:45:32+00:00</updated>
<author>
<name>Alan Stern</name>
<email>stern@rowland.harvard.edu</email>
</author>
<published>2023-08-04T19:12:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=de28e469da75359a2bb8cd8778b78aa64b1be1f4'/>
<id>urn:sha1:de28e469da75359a2bb8cd8778b78aa64b1be1f4</id>
<content type='text'>
The usb_get_device_descriptor() routine reads the device descriptor
from the udev device and stores it directly in udev-&gt;descriptor.  This
interface is error prone, because the USB subsystem expects in-memory
copies of a device's descriptors to be immutable once the device has
been initialized.

The interface is changed so that the device descriptor is left in a
kmalloc-ed buffer, not copied into the usb_device structure.  A
pointer to the buffer is returned to the caller, who is then
responsible for kfree-ing it.  The corresponding changes needed in the
various callers are fairly small.

Signed-off-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Link: https://lore.kernel.org/r/d0111bb6-56c1-4f90-adf2-6cfe152f6561@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>usb: core: hcd: Fix return value check in usb_hcd_setup_local_mem()</title>
<updated>2022-11-29T07:56:09+00:00</updated>
<author>
<name>Yang Yingliang</name>
<email>yangyingliang@huawei.com</email>
</author>
<published>2022-11-25T06:41:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=3c347cdafa3db43337870006e5c2d7b78a8dae20'/>
<id>urn:sha1:3c347cdafa3db43337870006e5c2d7b78a8dae20</id>
<content type='text'>
If dmam_alloc_attrs() fails, it returns NULL pointer and never
return ERR_PTR(), so repleace IS_ERR() with IS_ERR_OR_NULL()
and if it's NULL, returns -ENOMEM.

Fixes: 9ba26f5cecd8 ("ARM: sa1100/assabet: move dmabounce hack to ohci driver")
Signed-off-by: Yang Yingliang &lt;yangyingliang@huawei.com&gt;
Link: https://lore.kernel.org/r/20221125064120.2842452-1-yangyingliang@huawei.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>usb: host: Initiate urb ep with udev ep0</title>
<updated>2022-08-31T07:07:53+00:00</updated>
<author>
<name>Khalid Masum</name>
<email>khalid.masum.92@gmail.com</email>
</author>
<published>2022-08-24T20:31:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9013d8fc0ad91dc369f5b8ea708b9b068aa5d434'/>
<id>urn:sha1:9013d8fc0ad91dc369f5b8ea708b9b068aa5d434</id>
<content type='text'>
Currently we look up for endpoint in a table and initate urb endpoint
with it. This is unnecessary because the lookup will always result in
endpoint 0.

Suggested-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Acked-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Khalid Masum &lt;khalid.masum.92@gmail.com&gt;
Link: https://lore.kernel.org/r/20220824203107.14908-1-khalid.masum.92@gmail.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>usb/hcd: Fix dma_map_sg error check</title>
<updated>2022-08-19T09:10:23+00:00</updated>
<author>
<name>Jack Wang</name>
<email>jinpu.wang@ionos.com</email>
</author>
<published>2022-08-19T06:07:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=4dce3b375179fdd4aba2191be11ace90ef0ec6d6'/>
<id>urn:sha1:4dce3b375179fdd4aba2191be11ace90ef0ec6d6</id>
<content type='text'>
dma_map_sg return 0 on error.

Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Cc: Kishon Vijay Abraham I &lt;kishon@ti.com&gt;
Cc: Alexey Sheplyakov &lt;asheplyakov@basealt.ru&gt;
Cc: Stephen Boyd &lt;swboyd@chromium.org&gt;
Cc: Weitao Wang &lt;WeitaoWang-oc@zhaoxin.com&gt;
Cc: Matthias Kaehlcke &lt;mka@chromium.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Jack Wang &lt;jinpu.wang@ionos.com&gt;
Link: https://lore.kernel.org/r/20220819060801.10443-7-jinpu.wang@ionos.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'dma-mapping-5.20-2022-08-06' of git://git.infradead.org/users/hch/dma-mapping</title>
<updated>2022-08-06T17:56:45+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-08-06T17:56:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=c993e07be023acdeec8e84e2e0743c52adb5fc94'/>
<id>urn:sha1:c993e07be023acdeec8e84e2e0743c52adb5fc94</id>
<content type='text'>
Pull dma-mapping updates from Christoph Hellwig:

 - convert arm32 to the common dma-direct code (Arnd Bergmann, Robin
   Murphy, Christoph Hellwig)

 - restructure the PCIe peer to peer mapping support (Logan Gunthorpe)

 - allow the IOMMU code to communicate an optional DMA mapping length
   and use that in scsi and libata (John Garry)

 - split the global swiotlb lock (Tianyu Lan)

 - various fixes and cleanup (Chao Gao, Dan Carpenter, Dongli Zhang,
   Lukas Bulwahn, Robin Murphy)

* tag 'dma-mapping-5.20-2022-08-06' of git://git.infradead.org/users/hch/dma-mapping: (45 commits)
  swiotlb: fix passing local variable to debugfs_create_ulong()
  dma-mapping: reformat comment to suppress htmldoc warning
  PCI/P2PDMA: Remove pci_p2pdma_[un]map_sg()
  RDMA/rw: drop pci_p2pdma_[un]map_sg()
  RDMA/core: introduce ib_dma_pci_p2p_dma_supported()
  nvme-pci: convert to using dma_map_sgtable()
  nvme-pci: check DMA ops when indicating support for PCI P2PDMA
  iommu/dma: support PCI P2PDMA pages in dma-iommu map_sg
  iommu: Explicitly skip bus address marked segments in __iommu_map_sg()
  dma-mapping: add flags to dma_map_ops to indicate PCI P2PDMA support
  dma-direct: support PCI P2PDMA pages in dma-direct map_sg
  dma-mapping: allow EREMOTEIO return code for P2PDMA transfers
  PCI/P2PDMA: Introduce helpers for dma_map_sg implementations
  PCI/P2PDMA: Attempt to set map_type if it has not been set
  lib/scatterlist: add flag for indicating P2PDMA segments in an SGL
  swiotlb: clean up some coding style and minor issues
  dma-mapping: update comment after dmabounce removal
  scsi: sd: Add a comment about limiting max_sectors to shost optimal limit
  ata: libata-scsi: cap ata_device-&gt;max_sectors according to shost-&gt;max_sectors
  scsi: scsi_transport_sas: cap shost opt_sectors according to DMA optimal limit
  ...
</content>
</entry>
<entry>
<title>USB: HCD: Fix URB giveback issue in tasklet function</title>
<updated>2022-07-27T12:30:19+00:00</updated>
<author>
<name>Weitao Wang</name>
<email>WeitaoWang-oc@zhaoxin.com</email>
</author>
<published>2022-07-26T07:49:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=26c6c2f8a907c9e3a2f24990552a4d77235791e6'/>
<id>urn:sha1:26c6c2f8a907c9e3a2f24990552a4d77235791e6</id>
<content type='text'>
Usb core introduce the mechanism of giveback of URB in tasklet context to
reduce hardware interrupt handling time. On some test situation(such as
FIO with 4KB block size), when tasklet callback function called to
giveback URB, interrupt handler add URB node to the bh-&gt;head list also.
If check bh-&gt;head list again after finish all URB giveback of local_list,
then it may introduce a "dynamic balance" between giveback URB and add URB
to bh-&gt;head list. This tasklet callback function may not exit for a long
time, which will cause other tasklet function calls to be delayed. Some
real-time applications(such as KB and Mouse) will see noticeable lag.

In order to prevent the tasklet function from occupying the cpu for a long
time at a time, new URBS will not be added to the local_list even though
the bh-&gt;head list is not empty. But also need to ensure the left URB
giveback to be processed in time, so add a member high_prio for structure
giveback_urb_bh to prioritize tasklet and schelule this tasklet again if
bh-&gt;head list is not empty.

At the same time, we are able to prioritize tasklet through structure
member high_prio. So, replace the local high_prio_bh variable with this
structure member in usb_hcd_giveback_urb.

Fixes: 94dfd7edfd5c ("USB: HCD: support giveback of URB in tasklet context")
Cc: stable &lt;stable@kernel.org&gt;
Reviewed-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Weitao Wang &lt;WeitaoWang-oc@zhaoxin.com&gt;
Link: https://lore.kernel.org/r/20220726074918.5114-1-WeitaoWang-oc@zhaoxin.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>usb: xhci_plat_remove: avoid NULL dereference</title>
<updated>2022-07-27T12:29:14+00:00</updated>
<author>
<name>Alexey Sheplyakov</name>
<email>asheplyakov@basealt.ru</email>
</author>
<published>2022-07-22T14:17:00+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=d7de14d74d6551f0d097430f9893ce82ad17e5b8'/>
<id>urn:sha1:d7de14d74d6551f0d097430f9893ce82ad17e5b8</id>
<content type='text'>
Since commit 4736ebd7fcaff1eb8481c140ba494962847d6e0a ("usb: host:
xhci-plat: omit shared hcd if either root hub has no ports")
xhci-&gt;shared_hcd can be NULL, which causes the following Oops
on reboot:

[  710.124450] systemd-shutdown[1]: Rebooting.
[  710.298861] xhci-hcd xhci-hcd.2.auto: remove, state 4
[  710.304217] usb usb3: USB disconnect, device number 1
[  710.317441] xhci-hcd xhci-hcd.2.auto: USB bus 3 deregistered
[  710.323280] xhci-hcd xhci-hcd.2.auto: remove, state 1
[  710.328401] usb usb2: USB disconnect, device number 1
[  710.333515] usb 2-3: USB disconnect, device number 2
[  710.467649] xhci-hcd xhci-hcd.2.auto: USB bus 2 deregistered
[  710.475450] Unable to handle kernel NULL pointer dereference at virtual address 00000000000003b8
[  710.484425] Mem abort info:
[  710.487265]   ESR = 0x0000000096000004
[  710.491060]   EC = 0x25: DABT (current EL), IL = 32 bits
[  710.496427]   SET = 0, FnV = 0
[  710.499525]   EA = 0, S1PTW = 0
[  710.502716]   FSC = 0x04: level 0 translation fault
[  710.507648] Data abort info:
[  710.510577]   ISV = 0, ISS = 0x00000004
[  710.514462]   CM = 0, WnR = 0
[  710.517480] user pgtable: 4k pages, 48-bit VAs, pgdp=00000008b0050000
[  710.523976] [00000000000003b8] pgd=0000000000000000, p4d=0000000000000000
[  710.530961] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[  710.536551] Modules linked in: rfkill input_leds snd_soc_simple_card snd_soc_simple_card_utils snd_soc_nau8822 designware_i2s snd_soc_core dw_hdmi_ahb_audio snd_pcm_dmaengine arm_ccn panfrost ac97_bus gpu_sched snd_pcm at24 fuse configfs sdhci_of_dwcmshc sdhci_pltfm sdhci nvme led_class mmc_core nvme_core bt1_pvt polynomial tp_serio snd_seq_midi snd_seq_midi_event snd_seq snd_timer snd_rawmidi snd_seq_device snd soundcore efivarfs ipv6
[  710.575286] CPU: 7 PID: 1 Comm: systemd-shutdow Not tainted 5.19.0-rc7-00043-gfd8619f4fd54 #1
[  710.583822] Hardware name: T-Platforms TF307-MB/BM1BM1-A, BIOS 5.6 07/06/2022
[  710.590972] pstate: 40000005 (nZcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[  710.597949] pc : usb_remove_hcd+0x34/0x1e4
[  710.602067] lr : xhci_plat_remove+0x74/0x140
[  710.606351] sp : ffff800009f3b7c0
[  710.609674] x29: ffff800009f3b7c0 x28: ffff000800960040 x27: 0000000000000000
[  710.616833] x26: ffff800008dc22a0 x25: 0000000000000000 x24: 0000000000000000
[  710.623992] x23: 0000000000000000 x22: ffff000805465810 x21: ffff000805465800
[  710.631149] x20: ffff000800f80000 x19: 0000000000000000 x18: ffffffffffffffff
[  710.638307] x17: ffff000805096000 x16: ffff00080633b800 x15: ffff000806537a1c
[  710.645465] x14: 0000000000000001 x13: 0000000000000000 x12: ffff00080378d6f0
[  710.652621] x11: ffff00080041a900 x10: ffff800009b204e8 x9 : ffff8000088abaa4
[  710.659779] x8 : ffff000800960040 x7 : ffff800009409000 x6 : 0000000000000001
[  710.666936] x5 : ffff800009241000 x4 : ffff800009241440 x3 : 0000000000000000
[  710.674094] x2 : ffff000800960040 x1 : ffff000800960040 x0 : 0000000000000000
[  710.681251] Call trace:
[  710.683704]  usb_remove_hcd+0x34/0x1e4
[  710.687467]  xhci_plat_remove+0x74/0x140
[  710.691400]  platform_remove+0x34/0x70
[  710.695165]  device_remove+0x54/0x90
[  710.698753]  device_release_driver_internal+0x200/0x270
[  710.703992]  device_release_driver+0x24/0x30
[  710.708273]  bus_remove_device+0xe0/0x16c
[  710.712293]  device_del+0x178/0x390
[  710.715797]  platform_device_del.part.0+0x24/0x90
[  710.720514]  platform_device_unregister+0x30/0x50
[  710.725232]  dwc3_host_exit+0x20/0x30
[  710.728907]  dwc3_remove+0x174/0x1b0
[  710.732494]  platform_remove+0x34/0x70
[  710.736254]  device_remove+0x54/0x90
[  710.739840]  device_release_driver_internal+0x200/0x270
[  710.745078]  device_release_driver+0x24/0x30
[  710.749359]  bus_remove_device+0xe0/0x16c
[  710.753380]  device_del+0x178/0x390
[  710.756881]  platform_device_del.part.0+0x24/0x90
[  710.761598]  platform_device_unregister+0x30/0x50
[  710.766314]  of_platform_device_destroy+0xe8/0x100
[  710.771119]  device_for_each_child_reverse+0x70/0xc0
[  710.776099]  of_platform_depopulate+0x48/0x90
[  710.780468]  __dwc3_of_simple_teardown+0x28/0xe0
[  710.785099]  dwc3_of_simple_shutdown+0x20/0x30
[  710.789555]  platform_shutdown+0x30/0x40
[  710.793490]  device_shutdown+0x138/0x32c
[  710.797425]  __do_sys_reboot+0x1c4/0x2ac
[  710.801362]  __arm64_sys_reboot+0x30/0x40
[  710.805383]  invoke_syscall+0x50/0x120
[  710.809146]  el0_svc_common.constprop.0+0x68/0x124
[  710.813950]  do_el0_svc+0x3c/0xcc
[  710.817275]  el0_svc+0x60/0x12c
[  710.820428]  el0t_64_sync_handler+0xc0/0x13c
[  710.824710]  el0t_64_sync+0x18c/0x190
[  710.828386] Code: a9025bf5 f942c420 f9001fe0 d2800000 (b943ba62)
[  710.834498] ---[ end trace 0000000000000000 ]---
[  710.875958] pstore: crypto_comp_compress failed, ret = -22!
[  710.895047] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[  710.902757] Kernel Offset: disabled
[  710.906255] CPU features: 0x800,00004811,00001082
[  710.910971] Memory Limit: none
[  710.927474] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

To avoid the problem check for NULL in usb_remove_hcd.

Fixes: 4736ebd7fcaf ("usb: host: xhci-plat: omit shared hcd if either root hub has no ports")
Signed-off-by: Alexey Sheplyakov &lt;asheplyakov@basealt.ru&gt;
Link: https://lore.kernel.org/r/20220722141700.1271439-1-asheplyakov@basealt.ru
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>ARM: sa1100/assabet: move dmabounce hack to ohci driver</title>
<updated>2022-07-07T16:18:47+00:00</updated>
<author>
<name>Arnd Bergmann</name>
<email>arnd@arndb.de</email>
</author>
<published>2022-02-03T08:36:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.radix-linux.su/kernel/linux.git/commit/?id=9ba26f5cecd86c85551a5120529c2f548099100f'/>
<id>urn:sha1:9ba26f5cecd86c85551a5120529c2f548099100f</id>
<content type='text'>
The sa1111 platform is one of the two remaining users of the old Arm
specific "dmabounce" code, which is an earlier implementation of the
generic swiotlb.

Linus Walleij submitted a patch that removes dmabounce support from
the ixp4xx, and I had a look at the other user, which is the sa1111
companion chip.

Looking at how dmabounce is used, I could narrow it down to one driver
one three machines:

 - dmabounce is only initialized on assabet/neponset, jornada720 and
   badge4, which are the platforms that have an sa1111 and support
   DMA on it.

 - All three of these suffer from "erratum #7" that requires only
   doing DMA to half the memory sections based on one of the address
   lines, in addition, the neponset also can't DMA to the RAM that
   is connected to sa1111 itself.

 - the pxa lubbock machine also has sa1111, but does not support DMA
   on it and does not set dmabounce.

 - only the OHCI and audio devices on sa1111 support DMA, but as
   there is no audio driver for this hardware, only OHCI remains.

In the OHCI code, I noticed that two other platforms already have
a local bounce buffer support in the form of the "local_mem"
allocator. Specifically, TMIO and SM501 use this on a few other ARM
boards with 16KB or 128KB of local SRAM that can be accessed from the
OHCI and from the CPU.

While this is not the same problem as on sa1111, I could not find a
reason why we can't re-use the existing implementation but replace the
physical SRAM address mapping with a locally allocated DMA buffer.

There are two main downsides:

 - rather than using a dynamically sized pool, this buffer needs
   to be allocated at probe time using a fixed size. Without
   having any idea of what it should be, I picked a size of
   64KB, which is between what the other two OHCI front-ends use
   in their SRAM. If anyone has a better idea what that size
   is reasonable, this can be trivially changed.

 - Previously, only USB transfers to unaddressable memory needed
   to go through the bounce buffer, now all of them do, which may
   impact runtime performance for USB endpoints that do a lot of
   transfers.

On the upside, the local_mem support uses write-combining buffers,
which should be a bit faster for transfers to the device compared to
normal uncached coherent memory as used in dmabounce.

Cc: Linus Walleij &lt;linus.walleij@linaro.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Christoph Hellwig &lt;hch@infradead.org&gt;
Cc: Laurentiu Tudor &lt;laurentiu.tudor@nxp.com&gt;
Cc: linux-usb@vger.kernel.org
Signed-off-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Acked-by: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Signed-off-by: Christoph Hellwig &lt;hch@lst.de&gt;
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