Re: [PATCH] mmc: tegra: Mark 64-bit DMA broken on Tegra124

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On 08/31/2016 10:23 AM, Thierry Reding wrote:
From: Thierry Reding <treding@xxxxxxxxxx>

According to the TRM, the SD/MMC controller on Tegra124 supports 34-bit
addressing, but testing shows that this doesn't work. On a device which
has more than 2 GiB of RAM and LPAE enabled, buffer allocations can use
addresses above the 32-bit boundary.

One way to work around this would be to enable IOMMU physical to virtual
address translations for the SD/MMC controllers, but that's not easy to
implement without breaking existing use-cases. It's also not obvious why
34-bit addressing doesn't work as advertised. In order to fix this for
existing users, add the SDHCI_QUIRK2_BROKEN_64_BIT_DMA quirk for now.

Acked-by: Stephen Warren <swarren@xxxxxxxxxx>
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