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Subject: Re: [PATCH 2/3] dma-mapping: don't return errors from
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To: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>, iommu@lists.linux.dev,
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From: Robin Murphy <robin.murphy@arm.com>
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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.