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Date:   Tue, 22 Sep 2020 10:49:34 +0200
From:   Thomas Bogendoerfer <tsbogend@alpha.franken.de>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Joonyoung Shim <jy0922.shim@samsung.com>,
        Seung-Woo Kim <sw0312.kim@samsung.com>,
        Ben Skeggs <bskeggs@redhat.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Tomasz Figa <tfiga@chromium.org>,
        Matt Porter <mporter@kernel.crashing.org>,
        iommu@lists.linux-foundation.org,
        Stefan Richter <stefanr@s5r6.in-berlin.de>,
        linux1394-devel@lists.sourceforge.net, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
        linux-parisc@vger.kernel.org, linux-samsung-soc@vger.kernel.org,
        nouveau@lists.freedesktop.org, netdev@vger.kernel.org,
        linux-scsi@vger.kernel.org, linux-mm@kvack.org,
        alsa-devel@alsa-project.org
Subject: Re: [PATCH 07/18] 53c700: improve non-coherent DMA handling
Message-ID: <20200922084934.GB8477@alpha.franken.de>
References: <20200915155122.1768241-1-hch@lst.de>
 <20200915155122.1768241-8-hch@lst.de>
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On Tue, Sep 15, 2020 at 05:51:11PM +0200, Christoph Hellwig wrote:
> Switch the 53c700 driver to only use non-coherent descriptor memory if it
> really has to because dma_alloc_coherent fails.  This doesn't matter for
> any of the platforms it runs on currently, but that will change soon.
> 
> To help with this two new helpers to transfer ownership to and from the
> device are added that abstract the syncing of the non-coherent memory.
> The two current bidirectional cases are mapped to transfers to the
> device, as that appears to what they are used for.  Note that for parisc,
> which is the only architecture this driver needs to use non-coherent
> memory on, the direction argument of dma_cache_sync is ignored, so this
> will not change behavior in any way.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/scsi/53c700.c | 113 +++++++++++++++++++++++-------------------
>  drivers/scsi/53c700.h |  17 ++++---
>  2 files changed, 72 insertions(+), 58 deletions(-)

Tested-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]