On Tue, 26 Mar 2013, Arnd Bergmann wrote: > I think it's a horrible mess and if anyone has an idea of what the > right solution is, we should probably implement that, but from what > I see here, setting a 32-bit dma mask unless there is already one > is a reasonable choice. Okay. > > Don't forget that EHCI is theoretically capable of using 64-bit DMA. > > This may not matter for any of the platforms you're concerned about > > now, but it may matter in the future. > > Ah, I wasn't aware of that. I had previously used a platform EHCI on > PowerPC64 and the hardware manual said that it was 32-bit only. > Apparently the chip designers screwed up there. It's not as bad as that. Until recently, EHCI hardware didn't support the 64-bit option at all, or if it did, the support was buggy. Even now, I don't think it is very widespread. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
