linux-kernel - Re: [PATCH v3 3/4] ARM: dma-mapping: Switch to physical address mapping callbacks

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Message-ID: <20250917113248.GA1086830@nvidia.com>
Date: Wed, 17 Sep 2025 08:32:48 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Leon Romanovsky <leon@...nel.org>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>, iommu@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Russell King <linux@...linux.org.uk>
Subject: Re: [PATCH v3 3/4] ARM: dma-mapping: Switch to physical address
 mapping callbacks

On Wed, Sep 17, 2025 at 01:36:44PM +0300, Leon Romanovsky wrote:
> On Tue, Sep 16, 2025 at 03:46:17PM -0300, Jason Gunthorpe wrote:
> > On Tue, Sep 16, 2025 at 10:32:06AM +0300, Leon Romanovsky wrote:
> > > +	if (!dev->dma_coherent &&
> > > +	    !(attrs & (DMA_ATTR_SKIP_CPU_SYNC | DMA_ATTR_MMIO)))
> > > +		__dma_page_cpu_to_dev(phys_to_page(phys), offset, size, dir);
> > 
> > I'd keep going and get rid of the page here too, maybe as a second
> > patch in this series:
> 
> Thanks, it is always unclear how far to go with cleanups.

IMHO to maximally support what Matthew is working on I'd remove all
the struct page things and prefer the pfn/phys variations from the MM
side.

After this the only thing left is the kmap_high_get(), and I'm not
sure what becomes of WANT_PAGE_VIRTUAL in a memdesc world..

Jason