Hi Marek, On 10/11/2015 02:18 AM, Marek Vasut wrote:
Then you'd also need means to allocate variables to aligned memory location to prevent invalid cache flush. (Linux does this with it's DMA API). We are much simpler and thus this abstraction is still not available. I wonder if the overhead of DMA API would be high or not for U-Boot.
I see most people use memalign(ARCH_DMA_MINALIGN, len) in u-boot to allocate DMA buffers so that they are cache aligned.
It is even worse if the cache flush operators permit incorrect cache flushes or invalidations. Like I mentioned before, this can lead to hard to debug problems when using DMA (at least on ARM).
I would suggest debug check should be left as for debug only. The definition of common functions should be kept as it is more important than coding style.
I debugged DMA issues a lot in the past until I realized the importance of aligned buffers. So there should be a developer's guideline.
But it is even much more difficult when something you believed does not work as expected, what is taken as common sense. It will trap a lot of developers when they called your flush cache functions but was skipped just because, eg, the end of packets are not aligned which is usually the case.
I would suggest that, with the best of my knowledge, please change the range check to a debug probe, and restore the cache flush functions to the common definition.
Best regards, Thomas _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
