Hi Russel, On Thu, Apr 28, 2011 at 11:48 AM, Gupta, Ramesh <grgupta@xxxxxx> wrote: > Hi Russel, > > On Thu, Apr 28, 2011 at 8:40 AM, Russell King - ARM Linux > <linux@xxxxxxxxxxxxxxxx> wrote: >> On Fri, Apr 15, 2011 at 06:26:40AM -0500, Gupta, Ramesh wrote: >>> Russell, >>> >>> On Thu, Apr 14, 2011 at 5:30 PM, Russell King - ARM Linux >>> <linux@xxxxxxxxxxxxxxxx> wrote: >>> > On Thu, Apr 14, 2011 at 04:52:48PM -0500, Fernando Guzman Lugo wrote: >>> >> From: Ramesh Gupta <grgupta@xxxxxx> >>> >> >>> >> This patch is to flush the iommu page table entries from L1 and L2 >>> >> caches using dma_map_single. This also simplifies the implementation >>> >> by removing the functions flush_iopgd_range/flush_iopte_range. >>> > >>> > No. This usage is just wrong. If you're going to use the DMA API then >>> > unmap it, otherwise the DMA API debugging will go awol. >>> > >>> >>> Thank you for the comments, this particular memory is always a write >>> from the A9 for MMU programming and >>> only read from the slave processor, that is the reason for not calling >>> the unmap. I can re-look into the changes to call >>> unmap in a proper way as this impacts the DMA API. >>> Are there any other ways to perform only flush the memory from L1/L2 caches? >> >> We _could_ invent a new API to deal with this, which is probably going >> to be far better in the longer term for page table based iommus. That's >> going to need some thought - eg, do we need to pass a struct device >> argument for the iommu cache flushing so we know whether we need to flush >> or not (eg, if we have cache coherent iommus)... my apologies for a late mail on this topic. do you think of any other requirements for this new API? Could we use the existing dmac_flush_range(), outer_flush_range() for this purpose instead of a new API? I see a comment in the arch/arm/include/asm/cacheflush.h for _not_ to use these APIs directly, but I am not really understand the reason for that. I would appreciate any inputs on this. thank you and regards Ramesh Gupta G -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
