Re: [PATCH kernel v2 1/2] dma: Allow mixing bypass and normal IOMMU operation

[Alexey Kardashevskiy]

On 29/10/2020 04:21, Christoph Hellwig wrote:
> On Wed, Oct 28, 2020 at 05:55:23PM +1100, Alexey Kardashevskiy wrote:
> > It is passing an address of the end of the mapped area so passing a page
> > struct means passing page and offset which is an extra parameter and we do
> > not want to do anything with the page in those hooks anyway so I'd keep it
> > as is.
> >
> >
> > > and
> > >      maybe even hide the dma_map_direct inside it.
> >
> > Call dma_map_direct() from arch_dma_map_page_direct() if
> > arch_dma_map_page_direct() is defined? Seems suboptimal as it is going to
> > be bypass=true in most cases and we save one call by avoiding calling
> > arch_dma_map_page_direct(). Unless I missed something?
>
> C does not even evaluate the right hand side of a || expression if the
> left hand evaluates to true.

Right, this is what I meant. dma_map_direct() is inline and fast so I 
did not want it inside the arch hook which is not inline.


--
Alexey