On Mon, May 27, 2013 at 6:38 AM, Inki Dae <inki.dae@xxxxxxxxxxx> wrote: > Hi all, > > I have been removed previous branch and added new one with more cleanup. > This time, the fence helper doesn't include user side interfaces and cache > operation relevant codes anymore because not only we are not sure that > coupling those two things, synchronizing caches and buffer access between > CPU and CPU, CPU and DMA, and DMA and DMA with fences, in kernel side is a > good idea yet but also existing codes for user side have problems with badly > behaved or crashing userspace. So this could be more discussed later. > > The below is a new branch, > > https://git.kernel.org/cgit/linux/kernel/git/daeinki/drm-exynos.git/?h=dma-f > ence-helper > > And fence helper codes, > > https://git.kernel.org/cgit/linux/kernel/git/daeinki/drm-exynos.git/commit/? > h=dma-fence-helper&id=adcbc0fe7e285ce866e5816e5e21443dcce01005 > > And example codes for device driver, > > https://git.kernel.org/cgit/linux/kernel/git/daeinki/drm-exynos.git/commit/? > h=dma-fence-helper&id=d2ce7af23835789602a99d0ccef1f53cdd5caaae > > I think the time is not yet ripe for RFC posting: maybe existing dma fence > and reservation need more review and addition work. So I'd glad for somebody > giving other opinions and advices in advance before RFC posting. thoughts from a *really* quick, pre-coffee, first look: * any sort of helper to simplify single-buffer sort of use-cases (v4l) probably wouldn't want to bake in assumption that seqno_fence is used. * I guess g2d is probably not actually a simple use case, since I expect you can submit blits involving multiple buffers :-P * otherwise, you probably don't want to depend on dmabuf, which is why reservation/fence is split out the way it is.. you want to be able to use a single reservation/fence mechanism within your driver without having to care about which buffers are exported to dmabuf's and which are not. Creating a dmabuf for every GEM bo is too heavyweight. I'm not entirely sure if reservation/fence could/should be made any simpler for multi-buffer users. Probably the best thing to do is just get reservation/fence rolled out in a few drivers and see if some common patterns emerge. BR, -R > > Thanks, > Inki Dae > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
