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

From	Adrian Hunter <adrian.hunter@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host
Date	2016-03-16 10:40 +0100
Message-ID	<rdg5Q-77V-9@gated-at.bofh.it> (permalink)
References	<r9SMq-4VR-11@gated-at.bofh.it> <r9SMr-4VR-23@gated-at.bofh.it> <rdfjs-6uw-13@gated-at.bofh.it> <rdfCO-6Vb-9@gated-at.bofh.it>
Organization	Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki

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On 16/03/16 11:07, Arnd Bergmann wrote:
> 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().

So the logic this patch introduces will disable DMA in that case.  Would it
be better just to leave the DMA mask alone (as it does now for most sdhci
drivers) in the 32-bit case?

Thread

[PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host Alexandre Courbot <acourbot@nvidia.com> - 2016-03-07 03:10 +0100
  Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host Adrian Hunter <adrian.hunter@intel.com> - 2016-03-16 09:50 +0100
    Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host Arnd Bergmann <arnd@arndb.de> - 2016-03-16 10:10 +0100
      Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host Adrian Hunter <adrian.hunter@intel.com> - 2016-03-16 10:40 +0100
        Re: [PATCH v4 1/3] mmc: sdhci: Set DMA mask when adding host Arnd Bergmann <arnd@arndb.de> - 2016-03-16 11:10 +0100

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