On Wed, May 21, 2014 at 05:15:06PM +0100, Rob Herring wrote: > On Wed, May 21, 2014 at 10:48 AM, Arnd Bergmann <a...@arndb.de> wrote: > > On Wednesday 21 May 2014 10:26:01 Rob Herring wrote: > >> What are you checking against to cause a failure and what do you do on > >> failure? I'm guessing that PCI masks are compared to the mask of > >> parent bridges and PCI devices just set the mask to 32-bit if 64-bit > >> fails. That doesn't work if your mask needs to be somewhere between 32 > >> and 64-bit due to some bus constraints. Perhaps that's not something > >> we need to worry about until we see hardware with that condition. > > > > We should compare against the size returned by of_dma_get_range(). If > > the mask requested by the driver is larger than the mask of the bus > > it's attached on, dma_set_mask should fail. > > > > We can always allow 64-bit masks if the actual bus capability is enough > > to cover all the installed RAM. That is a relatively common case. > > Agreed. However, if we check dma-ranges, it may be large enough for > "all of RAM", but less than a full 64-bit. There is also the edge case > that you cannot set the size to 2^64, but only 2^64 - 1. That means > dma_set_mask(2^64 - 1) will always fail.
Size of 0 meaning all range? -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
