Hi Catalin, On Fri, Feb 21, 2014 at 10:53:08AM +0000, Catalin Marinas wrote: > On Fri, Feb 21, 2014 at 09:58:27AM +0000, Zhou Zhu wrote: > > We faced one issue using memcpy for memory type DEVICE_nGnRnE > > (pgprot_noncached). If the address is not aligned, exception would > > happen due to the alignment of this type could not be handled by hardware. > > Indeed, that's expected. This memory type is the equivalent of Strongly > Ordered. > > > Is there any plan and ongoing patch to support this or we need to keep > > address aligned for memcpy using pgprot_noncached memory in drivers? > > You either change the memory type to pgprot_writecombine() or use the > right API (memcpy_toio/memcpy_fromio, these could be further optimised, > similar to powerpc for example, but I didn't get there yet). How should we handle Device Memory with copy_from_user / copy_to_user? Should we follow the same scheme and create copy_from_user_io / copy_to_user_io, or rather enforce that the stock routines handle alignment? Thanks, Mike -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
