On 2020/2/4 下午8:52, Jason Gunthorpe wrote:
On Tue, Feb 04, 2020 at 04:28:27PM +0800, Jason Wang wrote:
On 2020/2/4 下午4:21, Zhu Lingshan wrote:
+static const struct dma_map_ops vdpasim_dma_ops = {
+ .map_page = vdpasim_map_page,
+ .unmap_page = vdpasim_unmap_page,
+ .alloc = vdpasim_alloc_coherent,
+ .free = vdpasim_free_coherent,
+};
+
Hey Jason,
IMHO, it would be nice if dma_ops of the parent device could be re-used.
vdpa_device is expecting to represent a physical device except this
simulator, however, there are not enough information in vdpa_device.dev
to indicating which kind physical device it attached to. Namely
get_arch_dma_ops(struct bus type) can not work on vdpa_device.dev. Then
it seems device drivers need to implement a wrap of dma_ops of parent
devices. Can this work be done in the vdpa framework since it looks like
a common task? Can "vd_dev->vdev.dev.parent = vdpa->dev->parent;" in
virtio_vdpa_probe() do the work?
Thanks,
BR
Zhu Lingshan
Good catch.
I think we can.
IMHO you need to specify some 'dma_device', not try and play tricks
with dma_ops, or assuming the parent is always the device used for
dma.
Jason
Right, this is what in my mind and discussed in the vhost-vdpa thread.
Will go this way.
Thanks
