linux-kernel - Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host

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Date:	Wed, 16 Mar 2016 10:07:01 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Alexandre Courbot <acourbot@...dia.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	gnurou@...il.com
Subject: Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host

On Wednesday 16 March 2016 10:43:33 Adrian Hunter wrote:
> > +
> > +     /* 32-bit mask as default & fallback */
> > +     if (ret) {
> > +             ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
> 
> What happens if device enumeration (e.g. of_dma_configure) has already set a
> more restrictive DMA mask?
> 
> 

In this case, dma_set_mask_and_coherent() is supposed to check the
bus properties settings again and fail dma_set_mask_and_coherent().

We currently don't do that on ARM, which is a bug.

	Arnd