Re: [PATCH] rpmsg: compute number of buffers to allocate from vrings

[Ohad Ben-Cohen <ohad@wizery.com>]

Hi Suman,

On Tue, Aug 12, 2014 at 7:19 PM, Suman Anna <s-anna@ti.com> wrote:
> Yes, I was playing around with using less buffers in the remoteproc
> resource table for the vrings. The remoteproc virtio code creates the
> vrings using the number of buffers based on .num field value of struct
> fw_rsc_vdev_vring in the resource table. The virtio rpmsg probe code
> though tries to set up the receive buffers for the same virtqueue based
> on the current hard-coded value of 512 buffers and virtqueue_add_inbuf
> would fail as the virtqueue is created with less number of buffers and
> throws a WARN_ON.

Gotcha - thanks for the details.

Limiting the number of buffers in case the vrings are too small makes
sense, but let's use RPMSG_NUM_BUFS as an upper bound, so wacky
resource tables won't trigger unreasonable memory waste.

Something in the lines of:

vrp->num_bufs = min(PMSG_NUM_BUFS, virtqueue_get_vring_size(vrp->rvq) * 2);

Should probably do the trick.

Does this satisfy your requirement?

Thanks,
Ohad.