Subject: Re: [PATCH 22/22] mtd: rawnand: Use dma_alloc_noncoherent() for dma buffer

From: 'Christoph Hellwig' <[email-masked]>
Date: Tue, 22 Feb 2022 14:16:10 +0100

On Tue, Feb 22, 2022 at 09:06:48AM +0000, David Laight wrote:
> From: Christoph Hellwig
> > Sent: 22 February 2022 08:47
> ...
> > > Hmm.. for this specific case, What about allocating two buffers
> > > for DMA_TO_DEVICE and DMA_FROM_DEVICE at initialization time?
> > 
> > That will work, but I don't see the benefit as you'd still need to call
> > dma_sync_single* before and after each data transfer.
> 
> For systems with an iommu that should save all the iommu setup
> for every transfer.

So does allocating a single buffer as in the patch we are replying to.