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Date:   Tue, 22 Feb 2022 09:45:30 +0100
From:   Christoph Hellwig <hch@lst.de>
To:     Baoquan He <bhe@redhat.com>
Cc:     Christoph Hellwig <hch@lst.de>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, akpm@linux-foundation.org, cl@linux.com,
        42.hyeyoo@gmail.com, penberg@kernel.org, rientjes@google.com,
        iamjoonsoo.kim@lge.com, vbabka@suse.cz, David.Laight@aculab.com,
        david@redhat.com, herbert@gondor.apana.org.au, davem@davemloft.net,
        linux-crypto@vger.kernel.org, steffen.klassert@secunet.com,
        netdev@vger.kernel.org, hca@linux.ibm.com, gor@linux.ibm.com,
        agordeev@linux.ibm.com, borntraeger@linux.ibm.com,
        svens@linux.ibm.com, linux-s390@vger.kernel.org, michael@walle.cc,
        linux-i2c@vger.kernel.org, wsa@kernel.org
Subject: Re: [PATCH 21/22] mmc: wbsd: Use dma_alloc_noncoherent() for dma
 buffer
Message-ID: <20220222084530.GA6210@lst.de>
References: <20220219005221.634-1-bhe@redhat.com> <20220219005221.634-22-bhe@redhat.com> <20220219071730.GG26711@lst.de> <20220220084044.GC93179@MiWiFi-R3L-srv>
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On Sun, Feb 20, 2022 at 04:40:44PM +0800, Baoquan He wrote:
> On 02/19/22 at 08:17am, Christoph Hellwig wrote:
> > On Sat, Feb 19, 2022 at 08:52:20AM +0800, Baoquan He wrote:
> > >  	if (request_dma(dma, DRIVER_NAME))
> > >  		goto err;
> > >  
> > > +	dma_set_mask_and_coherent(mmc_dev(host->mmc), DMA_BIT_MASK(24));
> > 
> > This also sets the streaming mask, but the driver doesn't seem to make
> > use of that.  Please document it in the commit log.
> 
> Thanks for reviewing. I will change it to dma_set_mask(), and describe
> this change in patch log.

No, if you change it, it should be dma_set_coherent_mask only as it is
not using streaming mappings.  I suspect dma_set_mask_and_coherent is
the right thing if the driver ever wants to use streaming mapping,
it would just need to be documented in the commit message.