On Fri, Mar 18, 2016 at 09:54:14AM +0800, Peter Chen wrote: > Although I don't know what kinds of bugs it may have, it may be > met before, otherwise, why most of platform drivers need to call > dma_set_coherent_mask or dma_coerce_mask_and_coherent explicitly See Documentation/DMA-API.txt, specifically the section starting Part Ic - DMA addressing limitations ------------------------------------ and also Documentation/DMA-API-HOWTO.txt, the section on DMA addressing limitations which provides further information. Drivers using DMA should be using dma_set_mask_and_coherent() _or_ one of dma_set_mask() and dma_set_coherent_mask() depending on which types of DMA they wish to perform. Drivers should not use dma_coerce_mask_and_coherent() except in exceptional circumstances: that function is more a marker that they or some bus/platform code is doing something wrong. -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- 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
