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a73f42850a
When do hot plug test on RK3566 Tablet with Type-C to Type-A receptacle. The dwc3 driver may receive the EXTCON_USB_HOST notifier with disconnect state twice occasionally, then it do dwc3_host_exit() repeatedly and cause panic issue with the following log: [ 260.793245] xhci-hcd xhci-hcd.4.auto: remove, state 4 [ 260.796706] xhci-hcd xhci-hcd.4.auto: USB bus 2 deregistered [ 260.797889] xhci-hcd xhci-hcd.4.auto: remove, state 1 [ 261.286875] xhci-hcd xhci-hcd.4.auto: USB bus 1 deregistered [ 261.289416] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000070 [ 261.290353] Mem abort info: [ 261.290624] ESR = 0x96000005 [ 261.290911] Exception class = DABT (current EL), IL = 32 bits [ 261.291501] SET = 0, FnV = 0 [ 261.291785] EA = 0, S1PTW = 0 [ 261.292065] Data abort info: [ 261.292323] ISV = 0, ISS = 0x00000005 [ 261.292660] CM = 0, WnR = 0 [ 261.293009] user pgtable: 4k pages, 39-bit VAs, pgdp = 000000005d271f4e [ 261.293610] [0000000000000070] pgd=0000000000000000, pud=0000000000000000 [ 261.294221] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 261.294726] Modules linked in: rknpu [ 261.295059] Process kworker/0:3 (pid: 1785, stack limit = 0x000000006a077ac4) [ 261.295693] CPU: 0 PID: 1785 Comm: kworker/0:3 Not tainted 4.19.161 #52 [ 261.296276] Hardware name: Rockchip RK3566 RK817 TABLET LP4X Board (DT) [ 261.296892] Workqueue: events_freezable __dwc3_set_mode [ 261.297371] pstate: 60c00009 (nZCv daif +PAN +UAO) [ 261.297817] pc : kernfs_find_ns+0x24/0x118 [ 261.298186] lr : kernfs_find_and_get_ns+0x3c/0x60 [ 261.298607] sp : ffffff800f90bbd0 ... [ 261.411635] [ 261.411780] Call trace: [ 261.412026] kernfs_find_ns+0x24/0x118 [ 261.412366] kernfs_find_and_get_ns+0x3c/0x60 [ 261.412757] sysfs_unmerge_group+0x20/0x60 [ 261.413125] dpm_sysfs_remove+0x3c/0x78 [ 261.413471] device_del+0x98/0x3f8 [ 261.413778] platform_device_del+0x2c/0xa8 [ 261.414139] platform_device_unregister+0x14/0x30 [ 261.414561] dwc3_host_exit+0x78/0x90 [ 261.414893] __dwc3_set_mode+0x39c/0x3a0 [ 261.415250] process_one_work+0x1a0/0x418 [ 261.415611] worker_thread+0x32c/0x3e0 [ 261.415950] kthread+0x12c/0x158 [ 261.416247] ret_from_fork+0x10/0x18 This patch checks the drd_connected status before handle disconnect process for host to avoid duplicating unregister platform device. Signed-off-by: William Wu <william.wu@rock-chips.com> Change-Id: I815d800febea89dbf1f5f84eba8efd9e910e3e9a
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.