Commit Graph

111 Commits

Author SHA1 Message Date
Yonghua Huang
1f17d0f4ac DM: xHCI: Check trb pointer before use it
The trb pointer may be NULL when get the address from user space, add
the pointer check before use the trb.

Tracked-On: #6172
Signed-off-by: Liu Long <long.liu@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2021-07-02 09:47:01 +08:00
Long Liu
e3fe3da273 DM USB: xHCI: Fix XHCI_GET_SLOT value check issue
Fix XHCI_GET_SLOT macro check slot valid function, when the
slot value is bigger than XHCI_MAX_SLOT set the slot value
to zero.

Tracked-On: #4711
Signed-off-by: Long Liu <long.liu@intel.com>
Reviewed-by: Yuan Liu <yuan1.liu@intel.com>
2020-06-09 15:57:56 +08:00
Xiaoguang Wu
06d3f4bcb2 DM USB: xHCI: [REVERTME] release memory on port resetting.
There is fd leakage during guest OS rebooting process, and this is
a WA patch to fix it. Formal patch will be made later.

Tracked-On: #4897
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
2020-06-05 21:19:05 +08:00
Long Liu
1672eca2b9 DM USB: xHCI: Drop commands if slot is disabled
From xHCI spec 4.5.3.2, the only command that software is
allowed to issue for the slot in disabled state is the Enable
Slot Command. Drop other commands in command handle function.

Tracked-On: #4711
Signed-off-by: Long Liu <long.liu@intel.com>
Reviewed-by: Yuan Liu <yuan1.liu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2020-06-05 15:31:05 +08:00
Junhao Gao
058b03c3a7 dm: fix memory free issue for xhci
remove uninitialized variable "dir", then make sure
"xfer->data","xfer->data[i].hcb","xfer->reqs" free correctly.

Tracked-On: #4154
Signed-off-by: Junhao Gao <junhao.gao@intel.com>
Reviewed-by: Yonghua Huang <yonghua.huang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-11-27 10:22:27 +08:00
Mingqiang Chi
5375a1613b dm:use acrn-dm logger function instread of printf
Use acrn-dm logger function instread of printf,
this helps the stability testing log capture.

Tracked-On: #4098
Signed-off-by: Mingqiang Chi <mingqiang.chi@intel.com>
Reviewed-by: Cao Minggui <minggui.cao@intel.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
2019-11-14 15:34:04 +08:00
Xiaoguang Wu
11f4a7267b DM USB: xHCI: support multiple ERST
This patch is used to support multiple Event Ring Segment Table (ERST).

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
52c17d634a DM USB: xHCI: rename some variables about ERST
This patch only changes some names of varaibles about Event Ring Segement
Table (ERST), and doesn't modify any code logic.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
06781b37e9 DM USB: dynamically allocate block count for struct usb_xfer
The block count of the struct usb_xfer is hard coded by the macro
USB_MAX_XFER_BLOCKS (1024), it wastes memory if 1024 blocks are
allocated for low speed transfer such as control transfer or interrupt
transfer. This patch introduces a new method to allocate different
number of blocks according to different endpoint type.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
f1b142e6e0 DM USB: xHCI: implement the emulation for overrun and underrun event
The overrun and underrun event are used in the timing control machanism,
this patch is used to implement this feature.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
7cb45bc968 DM USB: xHCI: refine the emulation logic for BEI bit in the TRB
The Block Event Interrupt (BEI) bit in the TRB descriptor could
delay the triggering of interrupt. For most OSes, the native
driver for xHCI will use this bit to optimize the IO performence,
due to reduction of number of interrupts.

But in Linux, the native xHCI driver for Intel brand controller
doesn't use this bit. It is fine for the native scenario due to
most work is completed by hardware. But in virtualization scenario,
it is almost impossible to support heavy data IO such as high
resolution video recording (ISOC transfer).

Hence, this issue is solved by a 'quirk' when the intel hardware is
emulated (when vendor id is set as 0x8086). For other cases, a
virtal hardware called 'ACRN xHCI' is emulated, and both Linux and
Windows will use BEI bit by default.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
685b1a7b66 DM USB: xHCI: fix emulation code for MFINDEX register
The old logic to emulate MFINDEX register is not right, this patch
is used to fix it.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
bda43ee352 DM USB: xHCI: rename the variable mf_prev_time
Just changed the name of the variable and didn't change any emulation
code logic.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
8949a5802a DM USB: introduce struct xhci_block for xHCI emulation
In the struct usb_block, there are some fields such as 'ccs',
'streamid', which should not be seen in the USB layer. This
patch intruduces new struct xhci_block to include the variables
for xHCI emulation.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
0110465416 DM USB: code clean: remove redundent code
When control transfer is detected and an unnecessary reset of
struct usb_xfer is conducted. This behavior is not necessary
and this patch is used to remove it.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
1352eca224 DM USB: introduce helper functions: index_inc and index_valid
Introduce helper functions to make code shorter and cleaner.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
236c23e418 DM USB: introduce enum type usb_block_type
In the process of USB data transfer, there three kinds of data blocks:
a. Non data block, which contains some control information;
b. Partial data block, which contains part of a large data chunk;
c. Full data block, which contains a complete data chunk.

In previous implementation, the differences mentioned above are described
by the usb_block::chained. But the 'chained' is concept in the xHCI area
and should not appear in the USB layer. This patch introduces enum type
usb_block_type to replace the 'chained' field in struct usb_block.

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
7445e404a8 DM USB: code clean: change some names of functions and variables
Some names of functions and variables are long and not exact, this
patch is used to change them, no logic code are affected. The
changing included:

usb_data_xfer -> usb_xfer
usb_data_xfer_block -> usb_block
usb_xfer_blk_stat -> usb_block_stat
usb_data_xfer_append -> usb_block_append
USB_XFER_BLK_* -> USB_BLOCK_*

Tracked-On: #3628
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-09-26 11:29:22 +08:00
Xiaoguang Wu
e188e1f245 DM USB: xHCI: fix an error in PORTSC emulation
When DM receives the Disable Slot command, according to xHCI spec,
the PP bit in PORTSC register should not be cleared.

Tracked-On: #3486
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-08-01 09:28:01 +08:00
Tianhua Sun
107c406baa dm: array bound checking to avoid buffer overflow
The array index of "epid" may be out of bounds if
"epid >= XHCI_MAX_ENDPOINTS", so bound check is
necessary before it is used.

Tracked-On: #3434
Signed-off-by: Tianhua Sun <tianhuax.s.sun@intel.com>
Reviewed-by: Yonghua Huang <yonghua.huang@intel.com>
Reviewed-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
2019-07-30 16:36:13 +08:00
Tianhua Sun
493ddefd47 dm: fix pointer not checked for null before use
this patch fix null pointer access issues.

Tracked-On: #3434
Signed-off-by: Tianhua Sun <tianhuax.s.sun@intel.com>
Reviewed-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
2019-07-30 16:36:13 +08:00
Xiaoguang Wu
7a3ea2ad89 DM USB: xHCI: fix corner case of short packet logic
The old logic identify the short packet complete status (CS) by
comparing the transfered bytes (TB) and the expected transfered
bytes (ETB), it is right only when no error happend. If error
appears, the TB may be less than the ETB, but DM should report
error CS instead of short packet CS.

Tracked-On: #3401
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-07-12 17:04:44 +08:00
Xiaoguang Wu
32d186ba68 DM USB: xHCI: add the resume state for PLS bits
Add resume state for the Port Link Status (PLS) bits.

Tracked-On: #3401
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-07-12 17:04:44 +08:00
Xiaoguang Wu
c3d4cc36e1 DM USB: xHCI: refine the logic of Stop Endpoint cmd
When the Stop Endpoint command is trapped, should not clear all
the data structure. Instead, only reset the ring buffer.

The reason is the xHCI may continue queue TRB without doing whole
initializing process again.

Tracked-On: #3401
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-07-12 17:04:44 +08:00
Xiaoguang Wu
31e23cd09c DM USB: clean up the assert usage
Remove assert in USB mediator code.

Tracked-On: #3252
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Shuo A Liu <shuo.a.liu@intel.com>
2019-06-26 22:50:38 +08:00
Tianhua Sun
b0015963f5 dm: fix some potential memory leaks
This patch is to fix some potential memory leak issues

1, free mrp if the mmio_rb_lookup() function return 0;
2, free memory allocated by strdup in some error case handling.

Tracked-On: #3277
Signed-off-by: Tianhua Sun <tianhuax.s.sun@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>
2019-06-19 08:39:55 +08:00
Xiaoguang Wu
5a9627ced8 DM USB: xHCI: refine the emulation of Stop Endpoint Command
Old implementation does nothing when Stop Endpoint cmd is received,
it is not right. The new implementation will cancel all the libusb
requests in processing.

Tracked-On: #3054
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-06-13 10:30:38 +08:00
Xiaoguang Wu
7dbde27615 DM USB: xHCI: use new isoch transfer implementation
The old implementation processes isoch TRB one by one, this method
can't support scenario which needs high performance, such as real
time USB camera video.

New implementions will compose all the isoch TRBs for one Door Bell
Ring, and give them to libusb as a single request. The test result
shows that this method could greatly improve the porfermance.

Tracked-On: #3054
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-06-13 10:30:38 +08:00
Xiaoguang Wu
adaed5c0e3 DM USB: xHCI: add 'chained' field in struct usb_data_xfer_block
The chained field could help to describe the relationship of USB
data blocks.

Tracked-On: #3054
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-06-13 10:30:38 +08:00
Xiaoguang Wu
b10ad4b311 DM USB: xHCI: refine the logic of CCS bit of PORTSC register
The CCS bit of PORTSC register should be set according to the mapped
native port connection status, use xdev->devices if equal NULL is not
enough due to devices only be clear in disable slot which can't reflect
the native connection state in some gaps.

Tracked-On: #3163
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-05-24 13:21:12 +08:00
Xiaoguang Wu
ae066689bb DM USB: xHCI: re-implement the emulation of extented capabilities
There are many quirks in Intel xHCI implementation and it is very hard
to debug under Microsoft Windows OS, hence use ACRN xHCI extented
capabilities as the default setting.

Tracked-On: #3163
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-05-24 13:21:12 +08:00
Arindam Roy
3d459dfddc DM: Fix minor issue of USB vendor ID
Provide a minor fix for following issue:
Emulated USB controller Vendor ID and Device ID are swapped.

Tracked-On: #3053
Signed-off-by: Arindam Roy <arindam.roy@intel.com>
Reviewed-by: Xu, Anthony <anthony.xu@intel.com>
2019-05-24 09:31:42 +08:00
Xiaoguang Wu
122685b7b9 DM USB: xHCI: refine the failure process logic of control transfer
The old logic to process control transfer failure only include two cases:
1 Short packet
2 Stall.
This patch includes all possible failures reported by Libusb and does
related emulation for UOS

Tracked-On: #2918
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-04-11 20:05:20 +08:00
Xiaoguang Wu
8bd7b9beae DM USB: xHCI: fix an logic error during USB reset
Should not set hci_address to zero during USB reset.

Tracked-On: #2922
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-04-11 13:21:30 +08:00
Xiaoguang Wu
63743d8b9b DM USB: xHCI: WA for an isochronous crash issue
The current xHCI mediator doesn't well support disable endpoint command.
This patch is one workaround for disable endpoint command to avoid
xHCI mediator to continue handle already dropped data.

Tracked-On: #2927
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-04-10 17:54:34 +08:00
Conghui Chen
e8dda1e914 DM USB: fix memory leak during reboot
1. free memory during pci_xhci_dev_destroy.
2. add libusb_free_device_list to free the list of devices previously
discovered using libusb_get_device_list().
3. fix possible memory corruption.

Tracked-On: #2892
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-04-04 18:35:02 +08:00
Conghui Chen
7ab6e7ea03 dm: usb: fix possible memory leak
fix possible memory leak for usb.

Tracked-On: #2704
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Reviewed-by: Yuan Liu <yuan1.liu@intel.com>
Reviewed-by: Yonghua Huang <yonghua.huang@intel.com>
2019-03-12 13:47:57 +08:00
Tianhua Sun
01c8f546e0 DM: xHCI: array bound checking before it is used
Array index of "vbdp_devs" may be out of bounds if
"i >= XHCI_MAX_VIRT_PORTS", so index checking is necessary.

Tracked-On: #1252
Signed-off-by: Tianhua Sun <tianhuax.s.sun@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2019-01-03 22:42:40 +08:00
Shuo A Liu
b3ad44d4c1 dm: use strnlen to replace strlen
Tracked-On: #2133
Signed-off-by: Shuo A Liu <shuo.a.liu@intel.com>
Reviewed-by: Yonghua Huang <yonghua.huang@intel.com>
2018-12-25 18:40:04 +08:00
Xiaoguang Wu
1d1d24345f DM USB: xHCI: change log level of some logs for S3 online debugging
S3 emulation is complicated and greatly dependent on system timing,
hence this patch changes log level for some important logs to help
online debugging (could output log by modifing launch_uos.sh and
without re-compiling)

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-20 20:22:25 +08:00
Xiaoguang Wu
d2627ecfcc DM USB: xHCI: fix an issues for failing to enumerate device
This is an obvious bug, which releases memory but still access the
data on the released memory. It is risky operation, and may result
failing to do normal enumlation process. This patch is used to fix
it.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-17 13:31:00 +08:00
Xiaoguang Wu
1c3344b782 DM USB: xHCI: change log level for S3 process
The USB S3 virtualization logic is complicated and heavily affected by system
timing. To make the debugging work easily, change related log level to facilitate
quick bug fixing.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-17 13:31:00 +08:00
Xiaoguang Wu
c2df4a8557 DM USB: xHCI: no wait logic implementation for S3
On Intel Apllo Lake platform, the VBus will drop after the SOC suspended,
hence during the SOS resuming process, there will be a disconnecting event
and a connecting event sent to each native USB device in order.

This patch will use new strategy for S3 resuming emultion.
  1. The DM set PORTSC register to 'no device attached' state when S3
     suspending started,
  2. SOS resuming starts and do nothing for device disconnecting event,
  3. 'Cache' device connecting event and don't report it to UOS,
  4. UOS believe no device attached due to PORTSC register state and
     begin to clear the resource allocated for the device before S3
     suspending,
  5. DM receives the Disable Slot command from UOS and report the 'cached'
     device connecting event to UOS, hence trigger the emulation behavior
     for the device.

The purpose of this strategy is to let UOS resuming proceed as quickly as
possible, which means the UI will be turned on quickly to user.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-14 19:40:44 +08:00
Xiaoguang Wu
82659831f0 DM USB: xHCI: refine emulation for command XHCI_CMD_RS
According to xHCI spec 5.4.1.1, this command hasn't ask to clear
PORTSC for R/S handling. So the PORTSC should always present the
physical usb bus status.

The old implementation changes the PORTSC according whether the
pci_xhci_dev_emu struct is allocated, it is not consistent with
spec and this patch is used to fix it.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-14 19:40:44 +08:00
Xiaoguang Wu
e5c98e6d9a DM USB: add usb_dev_path_cmp function for convenience
Comparing two USB devices' path is frequently used operation, abstract
it as an seperated function for convenience.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-14 19:40:44 +08:00
Xiaoguang Wu
6c1ca13767 DM USB: xHCI: remove the waiting 5 seconds wa for s3
This workaround will delay the UOS resuming for 5 seconds, this
behavior is not right and should be replaced by dynamic style.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-14 19:40:44 +08:00
Yang Liang
fbaecde6bb DM USB: xHCI: Fix banned API issue.
In USB mediator, sscanf, strtok and atoi API is banned, so replace them
with permitted API function.

Tracked-On: #1254
Signed-off-by: Yang Liang <liang3.yang@intel.com>
Reviewed-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Shuo Liu <shuo.a.liu@intel.com>
Reviewed-by: Yonghua Huang <yonghua.huang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-13 13:24:55 +08:00
Yang Liang
da0cf3af71 DM: xHCI: unbind slot id and ndevices relationship.
After mutiple usb devices send enable slot commnad and get slot id each
other, address device setup flow is not sorted by slot id. According to
current design, it will casue assert failure. This patch takes off this
restriction.

Tracked-On: #2017
Signed-off-by: Yang Liang <liang3.yang@intel.com>
Reviewed-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-12 09:11:29 +08:00
Xiaoguang Wu
9d4b5d7e1b DM USB: add some preparing time for xHCI emulation before resuming.
If the USB kernel drives and devices of SOS are not available and
functional ready after UOS is resumed from frozen state, the comming
USB command from UOS will cause a disaster because the DM has no
resourse to to emulation.

This patch add a dynamic time span (could change according to number
of native USB devices attached) to give USB drivers and devices of
SOS an opportunity to be ready.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-04 19:59:00 +08:00
Xiaoguang Wu
966c587260 DM USB: xHCI: fix potential NULL pointer issue.
During S3 process, the dev in the function pci_xhci_device_doorbell
may be set to NULL when disconnection is detected by DM. This patch
is used to remove this risk.

Tracked-On: #1893
Signed-off-by: Xiaoguang Wu <xiaoguang.wu@intel.com>
Reviewed-by: Liang Yang <liang3.yang@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
2018-12-04 19:59:00 +08:00