Hi all, I'm working on an MMC driver with a DMA capability. All has been working well, until at some point I've got a bus error, when the mmc driver had been handed in a buffer at 0x3000 physical RAM address. The reason is, that on Zynq arch bus masters cannot access RAM below 0x80000. Therefore my question: how shall I configure this in software? The way I found was to use ARM-specific struct dmabounce_device_info and implement its .needs_bounce() method to return true for those addresses. Is this the right way or is there a better / more straight-forward one? To do the above I have to enable CONFIG_DMABOUNCE, which then selects CONFIG_ZONE_DMA. Having done just that I suddenly discover, that 0x3000 buffers aren't used any more, so, I cannot actually verify my implementation :) Looking at ZONE_DMA it looks like it is still covering the whole RAM range (/proc/zoneinfo shows start_pfn=0 in zone DMA), so, I don't see why 0x3000 should be excluded now. So, is using the .needs_bounce() method the correct way to support DMA on this arch or is there a better one? Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
