On Friday 04 March 2016 19:38:42 Alexandre Courbot wrote: > Well that's far from the two-liner I had in mind to fix our bounce-buffers > problem with Tegra, but it feels correct. Testing for ACPI and PCI would be > appreciated (I am rather confident that ACPI will be ok, but the PCI part > should be reviewed by someone who knows better). > > 64-bit capable devices are supposed to set their own DMA mask. Currently > this does not happen for sdhci devices excepted for the two (sdhci-acpi > and sdhci-pci) that define a enable_dma() hook and do it there. However > this hook is called from several places while DMA mask is supposed to > be set only once ; for instance the sdhci-acpi driver maintains a flag > just to make sure the DMA mask is set only upon the first call of this > hook. > > For the vast majority of drivers that do not define a enable_dma() hook, the > default 32-bit DMA mask is used and there is a risk of using unneeded bounce > buffers on hosts capable of 64-bit addressing. > > The first patch adds a default DMA mask setting function that is called when > a DMA-capable host is added. It tries to set sane DMA masks according to the > device's reported capabilities. > > The addition of this function seems to make the same code in sdhci-acpi and > sdhci-pci redundant, so it is removed from these drivers. On top of making > this series a negative line count, it also removes one usage of the obsolete > pci_set_dma_mask() function. > > Thanks to Arnd for the insightful discussion that led to this. Looks great overall, much simpler and saner in the new version. I found one small bug, which appears to have been preexisting, but you moved it to a different file now. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
