sometimes I have panic

[leotian111]

Hi, I have some problems:
i use FL2000 work in MTK7621 chips under kernel-3.10; sometimes it works well and fltest have picture output; but sometime i get panic when insmod fl2000.ko.
it occurs in fl2000_intr_pipe_completion()-->queue_work().
CPU 0 Unable to handle kernel paging request at virtual address 00000080, epc == 82044bdc, ra == 82044ec4
i add printk in function fl2000_intr_pipe_completion(), i found that dev_ctx->intr_pipe_wq have become to NULL