io uring support for character device

[Changman Lee <cm224.lee@gmail.com>]

Hi List,

I'm CM Lee. I'm developing a custom character device managing pcie dma.
I've tried to use io uring for the char device which supports readv
and writev with synchronous and blocking manner and seek.
When I use a io uring with IORING_SETUP_IOPOLL and IORING_SETUP_SQPOLL
for reducing syscall overhead, a readv of the char device driver seems
to be not called. So I added a_ops->direct_IO when the device is
opened with O_DIRECT. But the result was the same.
This is my question.
Q1: Does io uring support a character device ?
Q2: Is it better to reimplement a device driver as block device type ?

Thanks,
CM