Re: [PATCH 2/3] dma-mapping: don't return errors from dma_set_seg_boundary

[Robin Murphy]

On 01/08/2024 2:33 pm, Christoph Hellwig wrote:
> On Thu, Aug 01, 2024 at 01:36:01PM +0100, Robin Murphy wrote:
> > I guess I assumed that the old block layer bodges in this area had been
> > cleaned up already - perhaps it *is* high time for whatever's left to grow
> > a proper understanding of whether a block device actually does its own DMA
> > or not.
>
> Can you point to a discussion on that?  The concepts here don't make
> quite sense to me.

No specific discussion, I just have a vague memory of hacks in the USB 
layer when I first started looking at this stuff 10 years ago... From a 
bit of digging to try to remind myself, I'm fairly sure that must have 
been the block bounce related stuff, which you cleaned up in 
6eb0233ec2d0 ("usb: don't inherity DMA properties for USB devices") a 
while back.

Cheers,
Robin.