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Date:   Mon, 6 Jul 2020 12:42:27 -0700
From:   Jonathan Lemon <jonathan.lemon@gmail.com>
To:     Christoph Hellwig <hch@lst.de>
Cc:     =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= <bjorn.topel@intel.com>,
        Magnus Karlsson <magnus.karlsson@intel.com>,
        iommu@lists.linux-foundation.org, netdev@vger.kernel.org,
        bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/4] dma-mapping: add a new dma_need_sync API
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 <20200629130359.2690853-2-hch@lst.de>
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On Mon, Jun 29, 2020 at 03:03:56PM +0200, Christoph Hellwig wrote:
> Add a new API to check if calls to dma_sync_single_for_{device,cpu} are
> required for a given DMA streaming mapping.
> 
> +::
> +
> +	bool
> +	dma_need_sync(struct device *dev, dma_addr_t dma_addr);
> +
> +Returns %true if dma_sync_single_for_{device,cpu} calls are required to
> +transfer memory ownership.  Returns %false if those calls can be skipped.

Hi Christoph -

Thie call above is for a specific dma_addr.  For correctness, would I
need to check every addr, or can I assume that for a specific memory
type (pages returned from malloc), that the answer would be identical?
-- 
Jonathan