Re: [PATCH net-next 2/7] dma: avoid expensive redundant calls for sync operations

From: Christoph Hellwig
Date: Mon Jan 29 2024 - 01:10:06 EST


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