Hi Maxime, On 13 February 2017 at 10:54, Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote: > On Sun, Feb 12, 2017 at 02:28:11PM +0200, Laurent Pinchart wrote: >> On Thursday 02 Feb 2017 11:31:56 Maxime Ripard wrote: >> > This patch add a config to support to create multi buffer for cma fbdev. >> > Such as double buffer and triple buffer. >> > >> > Cma fbdev is convient to add a legency fbdev. And still many Android >> > devices use fbdev now and at least double buffer is needed for these >> > Android devices, so that a buffer flip can be operated. It will need >> > some time for Android device vendors to abondon legency fbdev. So multi >> > buffer for fbdev is needed. >> >> How exactly do we expect Android to move away from fbdev if we add features to >> the fbdev compat layer ? I'd much rather make it clear to them that fbdev is a >> thing from the past and that they'd better migrate now. > > If your point is that merging this patch will slow down the Android > move away from fbdev, I disagree with that (obviously). > > I don't care at all about Android on my platform of choice, but don't > see how that merging this patch will change anything. > > Let's be honest, Android trees typically have thousands of patches on > top of mainline. Do you think a simple, 15 LoC, patch will make any > difference to vendors? If they want to stay on fbdev and have that > feature, they'll just merge this patch, done. So, in that case, why not just let them do that? They'd already have to add patches to use this, surely; we don't have anything in mainline kernels which allows people to actually use this larger allocation. Apart from software mmap() and using panning to do flips, but I'm taking it as a given that people shipping Android on their devices aren't using software rendering. > However, what I do see is that three different people/organisations > have now expressed interest in that feature, on three different > SoCs. If that patch needed a significant rework of the fbdev layer, > then yes, I might agree that it's not worth it. But in this case, it's > pretty trivial. > > The only people you're "punishing" here with that kind of concern are > the people who actually play fair and want not to have any patches and > everything upstream. I would hazard a guess that most users of this have out-of-tree GPU drivers. > I guess a much better strategy would be to provide an incentive to > moving to KMS. And I truely think there's one already, so it's just a > matter of time before people switch over. Fbdev emulation or not. The concern makes sense, but on the other hand, fbdev is deprecated: no new drivers, and no new features. Cheers, Daniel _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
