Re: [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in enable_dma()

From	Adrian Hunter <adrian.hunter@intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in enable_dma()
Date	2016-03-14 14:10 +0100
Message-ID	<rcApZ-4at-25@gated-at.bofh.it> (permalink)
References	<r9SMq-4VR-11@gated-at.bofh.it> <r9SMr-4VR-27@gated-at.bofh.it> <rapS2-1q3-15@gated-at.bofh.it> <rcrcZ-6vd-7@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 14/03/16 05:15, Alexandre Courbot wrote:
> On Tue, Mar 8, 2016 at 10:18 PM, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> On 07/03/16 04:07, Alexandre Courbot wrote:
>>> DMA mask will already be set by sdhci_set_dma_mask(), which
>>> is equivalent to the removed code since pci_set_dma_mask()
>>> expands to its DMA-API counterpart.
>>>
>>> There should also be no reason to set the DMA mask after probe.
>>
>> Let's run that by the PCI mailing list just to be sure.  The patches for
>> reference:
>>
>>         http://marc.info/?l=linux-mmc&m=145731654328126&w=2
>>         http://marc.info/?l=linux-mmc&m=145731654328128&w=2
>>
>> change the sdhci-pci driver to set the DMA mask once during probe instead of
>> every time during resume.  Is there any reason a PCI device driver might
>> need to set the DMA mask every time during resume?
> 
> Not seeing much reaction for this patchset. PCI being the only
> possible point of contention, can we maybe roll it into -next and see
> what happens?

+Rafael

Rafael, can you offer any thoughts on this:

PCI drivers that want to use DMA might call pci_set_master() in the pm
resume callback.  Some drivers (like sdhci-pci) also, presumably out of
convenience, set the DMA mask at the same time.  The question is: is it OK
instead to set the DMA mask just once during probe, or is there some other
reason the DMA mask needs to be set every time during resume?

Thread

[PATCH v4 0/3] mmc: sdhci: Set DMA mask properly Alexandre Courbot <acourbot@nvidia.com> - 2016-03-07 03:10 +0100
  [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in enable_dma() Alexandre Courbot <acourbot@nvidia.com> - 2016-03-07 03:10 +0100
    Re: [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in  enable_dma() Adrian Hunter <adrian.hunter@intel.com> - 2016-03-08 14:30 +0100
      Re: [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in enable_dma() Alexandre Courbot <gnurou@gmail.com> - 2016-03-14 04:20 +0100
        Re: [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in  enable_dma() Adrian Hunter <adrian.hunter@intel.com> - 2016-03-14 14:10 +0100
          Re: [PATCH v4 3/3] mmc: sdhci-pci: Do not set DMA mask in  enable_dma() Bjorn Helgaas <helgaas@kernel.org> - 2016-03-14 17:00 +0100
  Re: [PATCH v4 0/3] mmc: sdhci: Set DMA mask properly Adrian Hunter <adrian.hunter@intel.com> - 2016-03-16 14:00 +0100
  Re: [PATCH v4 0/3] mmc: sdhci: Set DMA mask properly Ulf Hansson <ulf.hansson@linaro.org> - 2016-03-16 14:10 +0100

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