On Tuesday 30 September 2014 20:39:34 Peter Chen wrote: > Thanks, Arnd. I had not thought setting dma mask is so complicated, yes, it > should check the return value, two things to confirm: > > - dma_coerce_mask_and_coherent or dma_set_mask_and_coherent, the only difference > of these two API is the first one do "dev->dma_mask = &dev->coherent_dma_mask;" > The reason you suggest choosing dma_set_mask_and_coherent is you do not want > assign dev->dma_mask? No, that is just the current definition on ARM32 with CONFIG_ARCH_MULTIPLATFORM, and that is going to change soon to be DT aware. dma_set_mask_and_coherent() is supposed to check whether the platform can support the respective mask and return an error if it cannot. > - The second parameter for dma_set_mask_and_coherent is DMA_BIT_MASK(32), is it > ok? > > I just a little confused of what's the operation is "hardcoding the dma mask"? dma_coerce_mask_and_coherent() will hardcode the dma mask and override whatever the platform says is necessary. Arnd -- 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
