On Thu, Jul 20, 2023 at 03:34:01PM +0800, Xuan Zhuo wrote: > On Wed, 19 Jul 2023 23:57:51 -0700, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > > On Thu, Jul 20, 2023 at 02:45:14PM +0800, Xuan Zhuo wrote: > > > virtqueue_dma_dev() return the device that working with the DMA APIs. > > > Then that can be used like other devices. So what is the problem. > > > > > > I always think the code path without the DMA APIs is the trouble for you. > > > > Because we now have an API where the upper level drivers sometimes > > see the dma device and sometimes not. > > No dma device is just for the old devices. > > The API without DMA dev are only compatible with older devices. We can't give up > these old devices, but we also have to embrace new features. > > > This will be abused and cause > > trouble sooner than you can say "layering". > > I don't understand what the possible trouble here is. > > When no dma device, the driver just does the same thing as before. > > Thanks. Instead of skipping operations, Christoph wants wrappers that do nothing for non dma case. -- MST
