On Friday 07 March 2014 11:55 AM, Rob Herring wrote: > On Thu, Mar 6, 2014 at 9:44 PM, Santosh Shilimkar > <santosh.shilimkar@xxxxxx> wrote: >> On Friday 07 March 2014 11:13 AM, Rob Herring wrote: >>> On Thu, Mar 6, 2014 at 3:19 AM, Santosh Shilimkar >>> <santosh.shilimkar@xxxxxx> wrote: >>>> The of_dma_is_coherent() helper parses the given DT device >>>> node to see if the "dma-coherent" property is supported and >>>> returns true or false accordingly. >>>> >>>> For the architectures which are fully dma coherent and don't need per device >>>> property, it can enable CONFIG_ARCH_IS_DMA_COHERENT config option which >>>> enables DMA coherent for all devices by default. >>> >>> This worries me. I killed off arch_is_coherent() for arm. Now we're >>> adding something back. Also, we already have HAVE_GENERIC_DMA_COHERENT >>> which is different, but the names will be confusing. MIPS also has >>> DMA_NONCOHERENT. >>> >> Thanks for comments Rob. I will address them in next version. >> Specifically about ARCH_IS_DMA_COHERENT, I wasn't very comfortable either >> while adding it. But as Arnd mentioned, there is a need to have a way >> for the arch's which are fully coherent to use coherent ops by default. >> >> Am not sure whats the best way to have such support without imposing >> any special updates on such arches. > > Thinking about this some more, if the arch is always coherent or > always non-coherent, then the default ops are always fine. In that > case set_arch_dma_coherent_ops is always a nop and of_dma_is_coherent > is a don't care. > Hmmm.. I guess you are right. In that case we can drop the need of config option. Regards, Santosh -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
