Dear Ilya Yanok, > Hi Marek, > > [sorry for copying, forget to CC the list] > > On Sat, Jun 16, 2012 at 2:29 AM, Marek Vasut <marek.va...@gmail.com> wrote: > > Hm, can't we just punch a hole in the MMU table at runtime instead of > > preallocating it like this? > > It's allocated at runtime now, do you mean allocate it on demand? Good > point, Probably we can malloc big enough block and make it uncached > directly from dma_alloc_coherent(). Is it what you suggest?
Kind of ... I mean rather insert an entry into MMU table at runtime that says "this region is uncached". But that'd need some hack in the mallocator now that I think about it. It might not be as simple as I thought at first. On the other hand, most MMUs allow you to allocate stuff with 4k density, which should be ok. > Also, what is this for? Can we not simply flush/invalidate the caches? > > > flush/invalidate can be racy for some hardware. Sometimes we need to write > some field to DMA descriptor and then read another one. And because one > cannot flush/invalidate individual bytes write/flush can destroy the field > updated by hardware. (Well, we can invalidate/read before write/flush but > that introduces a race). But that's shitty hardware. Do you really need to do it? Where? I fixed similar issue in fec_mxc.c recently. > > Regards, Ilya. Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
