Hi Nick, again thanks for your response in the 'arcmsr: code cleanup and some corrections' thread. Let us find a resolution here too. Is the original patch fine for you, or do you prefer not to take it? Tomas > On 02/18/2011 02:04 AM, FUJITA Tomonori wrote: > >> On Thu, 17 Feb 2011 16:05:37 +0100 >> Tomas Henzl <thenzl@xxxxxxxxxx> wrote: >> >> >> >>> the discussion is mostly if 'dma_alloc_coherent' >>> ... >>> dma_coherent = dma_alloc_coherent(&pdev->dev, acb->uncache_size, &dma_coherent_handle, GFP_KERNEL); >>> ... >>> returns a page address - dma_coherent with last, I think five bits, zeroed. >>> Could you help us with that? >>> >>> >> Documentation/DMA-API-HOWTO.txt is not clear enough? >> >> = >> dma_alloc_coherent returns two values: the virtual address which you >> can use to access it from the CPU and dma_handle which you pass to the >> card. >> >> The cpu return address and the DMA bus master address are both >> guaranteed to be aligned to the smallest PAGE_SIZE order which >> is greater than or equal to the requested size. This invariant >> exists (for example) to guarantee that if you allocate a chunk >> which is smaller than or equal to 64 kilobytes, the extent of the >> buffer you receive will not cross a 64K boundary. >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> > It's clear enough I think, I asked this question because Nick doesn't > have a "100% confidence in that.". So I wanted a help to convince him. > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
