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Subject: Re: [PATCH 2/2] arm: use swiotlb for bounce buffer on LPAE configs
From:   Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To:     Christoph Hellwig <hch@lst.de>,
        Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc:     Vignesh Raghavendra <vigneshr@ti.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-arm-kernel@lists.infradead.org, Roger Quadros <rogerq@ti.com>
Date:   Wed, 24 Jul 2019 19:23:50 +0200
In-Reply-To: <20190709142011.24984-3-hch@lst.de>
References: <20190709142011.24984-1-hch@lst.de>
         <20190709142011.24984-3-hch@lst.de>
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On Tue, 2019-07-09 at 07:20 -0700, Christoph Hellwig wrote:
> The DMA API requires that 32-bit DMA masks are always supported, but on
> arm LPAE configs they do not currently work when memory is present
> above 4GB.  Wire up the swiotlb code like for all other architectures
> to provide the bounce buffering in that case.
>=20
> Fixes: 21e07dba9fb11 ("scsi: reduce use of block bounce buffers").
> Reported-by: Roger Quadros <rogerq@ti.com>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Hi Chistoph,
Out of curiosity, what is the reason stopping us from using dma-direct/swio=
tlb
instead of arm_dma_ops altogether?

Regards,
Nicolas


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