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    SubjectRe: [PATCH v11] i2c: virtio: add a virtio i2c frontend driver
    On 01-07-21, 14:10, Jie Deng wrote:
    > I think a fixed number of sgs will make things easier to develop backend.

    Yeah, but it looks awkward to send a message buffer which isn't used
    at all. From protocol's point of view, it just looks wrong/buggy.

    The backend can just look at the number of elements received, they
    can either be 2 (in case of zero-length) transfer, or 3 (for
    read/write) and any other number is invalid.

    > If you prefer to parse the number of descriptors instead of using the msg
    > length to
    > distinguish the zero-length request from other requests, I'm OK to set a
    > limit.

    My concern is more about the specification here first.

    > if (!msgs[i].len) {
    >     sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
    >     if (msgs[i].flags & I2C_M_RD)
    >         sgs[outcnt + incnt++] = &msg_buf;
    >     else
    >         sgs[outcnt++] = &msg_buf;
    > }

    > > > +#ifdef CONFIG_PM_SLEEP
    > > You could avoid this pair of ifdef by creating dummy versions of below
    > > routines for !CONFIG_PM_SLEEP case. Up to you.
    > Thank you. I'd like to keep the same.



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