Hi Magnus, I noticed during randconfig testing that you enabled DMABOUNCE for the pci-rcar-gen2 driver as posted in this patch https://lkml.org/lkml/2014/2/5/30 I didn't see the original post unfortunately, but I fear we have to revert it and come up with a better solution, as your approach seems wrong on a number of levels: * We really don't want any new users of DMABOUNCE on ARM but instead leave it to the PXA/IXP/SA1100 based platforms using it today. * If your SoCs have an IOMMU, you should really use it, as that would give you much better performance than bounce buffers anyway * If the hardware is so screwed up that you have to use bounce buffers, use the SWIOTLB code that is reasonably modern. * The window base and size in the driver should not be hardcoded, as this is likely not a device specific property but rather an artifact of how it's connected. Use the standard "dma-ranges" property. * You should not need your own dma_map_ops in the driver. What you do there isn't really specific to your host but should live in some place where it can be shared with other drivers. * The implementation of the dma_map_ops is wrong: at the very least, you cannot use the dma_mask of the pci host when translating calls from the device, since each pci device can have a different dma mask that is set by the driver if it needs larger or smaller than 32-bit DMA space. * The block bounce code can't be enabled if CONFIG_BLOCK is disabled, this is how I noticed your changes. * The block layer assumes that it will bounce any highmem pages, but that isn't necessarily what you want here: if you have 2GB of lowmem space (CONFIG_VMSPLIT_2G) or more, you will also have lowmem pages that need bouncing. * (completely unrelated, I noticed you set up a bogus I/O space window. Don't do that, you will get get a panic if a device happens to use it. Not providing an resource should work fine though) On the bright side, your other changes in the same series all look good. Thanks especially for sorting out the probe() function, I was already wondering if we could change that the way you did. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
