Subject: Re: [PATCH 21/22] mmc: wbsd: Use dma_alloc_noncoherent() for dma buffer

From: Christoph Hellwig <[email-masked]>
Date: Tue, 22 Feb 2022 09:45:30 +0100

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.