Re: [PATCH 00/15] mmc: sdhci: Add 64-bit ADMA support

Arnd Bergmann
2014-10-30T10:00:27Z

On Thursday 30 October 2014 10:40:12 Adrian Hunter wrote:
> On 30/10/14 10:05, Arnd Bergmann wrote:
> > On Thursday 30 October 2014 09:25:54 Adrian Hunter wrote:
> >> On 21/10/14 12:26, Adrian Hunter wrote:
> >>> Hi
> >>>
> >>> Here are patches to add 64-bit ADMA support to the SDHCI driver.
> >>>
> >>> The patchset starts with 3 minor fixes related to SDHCI ADMA,
> >>> then there are 8 preparatory patches, then 3 main patches, then
> >>> the mmc_test "Badly aligned" tests are extended slightly.
> >>
> >> Hi Ulf
> >>
> >> Can you take these? Note that there was a V2 of
> >> "mmc: sdhci-acpi: Add 64-bit DMA support". Also
> >> that patch is dependent (for functionality not
> >> compilation) on a patch in v3.18-rc2 so it is slightly
> >> preferable if you pull v3.18-rc2 first.
> >
> > You still haven't addressed my comments about clearing
> > the SDHCI_USE_64_BIT_DMA flag if the platform finds that
> > hardware has set this bit incorrectly.
>
> Yes I did. I said there was no need:
>
> http://marc.info/?l=linux-mmc&m=141449082331402&w=2
>
> I would also note that the SDHCI spec does not say explicitly
> that a 64-bit device supports 32-bit DMA descriptors.
>
> If the hardware really is broken, the SDHCI_QUIRK2_BROKEN_64_BIT_DMA
> should be used.

You also said that the flag is defined to mean that 64-bit DMA
is working and that you want to show the warning when the hardware
and the firmware disagree about this. If you have an (at least)
50% chance that the hardware is lying, you really shouldn't believe
it.

Arnd