On Fri, Apr 15, 2016 at 11:01:08AM +0100, Catalin Marinas wrote: > On Fri, Apr 15, 2016 at 12:49:15PM +0300, Felipe Balbi wrote: > > Catalin Marinas <catalin.marinas@xxxxxxx> writes: > > > On Thu, Apr 14, 2016 at 12:46:47PM +0000, David Fisher wrote: > > >> dwc3 is in dual-role, with "synopsys,dwc3" specified in DT. > > >> > > >> When xhci is probed, initiated from dwc3/host.c (not DT), we get : > > >> xhci-hcd: probe of xhci-hcd.7.auto failed with error -5 > > >> This -EIO error originated from inside dma_set_mask() down in include/asm-generic/dma-mapping-common.h > > >> > > >> If "generic-xhci" is specified in DT instead, it probes fine as a host-only dwc3 > > >> The difference between DT initiated probe and dwc3 initiated probe is that > > >> when DT initiated probe gets to dma_supported, dma_supported is > > >> implemented by swiotlb_dma_supported (previously set up by a DT call to arch_dma_setup_ops). > > >> Whereas when dwc3 initiated xhci probe gets to dma_supported, arch_dma_setup_ops has not been called > > >> and dma_supported is only implemented by __dummy_dma_supported, returning 0. > > >> > > >> Bisecting finds the "bad" commit as > > >> 1dccb598df549d892b6450c261da54cdd7af44b4 (inbetween 4.4-rc1 and 4.4-rc2) > > >> --- a/arch/arm64/include/asm/dma-mapping.h > > >> --- a/arch/arm64/mm/dma-mapping.c > > >> > > >> Previous to this commit, dma_ops = &swiotlb_dma_ops was done in arm64_dma_init > > >> After this commit, the assignment is only done in arch_dma_setup_ops. > > > > > > This restriction was added on purpose and the arm64 __generic_dma_ops() > > > now has a comment: > > > > > > /* > > > * We expect no ISA devices, and all other DMA masters are expected to > > > * have someone call arch_setup_dma_ops at device creation time. > > > */ > > > > how ? > > Usually by calling arch_setup_dma_ops(). Or of_dma_configure(), I forgot to mention this (see the pci_dma_configure() function as an example). -- Catalin -- 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
