On Fri, Jan 26, 2024 at 07:13:05PM +0000, Robin Murphy wrote:

quoted

Can we have a comment that states this assumption along with the flag?
Because when it breaks, it will keep someone cursing for days why DMA
sometimes fails on their device before they find out it's not synced.
And then wondering why the code makes such silly assumptions...

Indeed, apologies if it wasn't totally clear, but I really was implying a 
literal "may skip sync if coherent and not using SWIOTLB (which matches 
dma-direct)" flag, documented as such, and not trying to dress it up as 
anything more generic. I just can't suggest a suitably concise name for 
that of the top of my head... :)

Yes, that seems like the right way to go.