Am Sonntag, den 05.04.2015, 21:41 +0200 schrieb Christian Gmeiner: > 2015-04-02 18:37 GMT+02:00 Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>: > > On Thu, Apr 02, 2015 at 05:30:44PM +0200, Lucas Stach wrote: > >> While this isn't the case on i.MX6 a single GPU pipe can have > >> multiple rendering backend states, which can be selected by the > >> pipe switch command, so there is no strict mapping between the > >> user "pipes" and the PIPE_2D/PIPE_3D execution states. > > > > This is good, because on Dove we have a single Vivante core which > > supports both 2D and 3D together. It's always bugged me that > > etnadrm has not treated cores separately from their capabilities. > > > > Today I finally got the idea how this multiple pipe stuff should be > done the right way - thanks Russell. > So maybe you/we need to rework how the driver is designed regarding > cores and pipes. > > On the imx6 we should get 3 device nodes each only supporting one pipe > type. On the dove we > should get only one device node supporting 2 pipes types. What do you think? > Sorry, but I strongly object against the idea of having multiple DRM device nodes for the different pipes. If we need the GPU2D and GPU3D to work together (and I can already see use-cases where we need to use the GPU2D in MESA to do things the GPU3D is incapable of) we would then need a lot more DMA-BUFs to get buffers across the devices. This is a waste of resources and complicates things a lot as we would then have to deal with DMA-BUF fences just to get the synchronization right, which is a no-brainer if we are on the same DRM device. Also it does not allow us to make any simplifications to the userspace API, so I can't really see any benefit. Also on Dove I think one would expect to get a single pipe capable of executing in both 2D and 3D state. If userspace takes advantage of that one could leave the sync between both engines to the FE, which is a good thing as this allows the kernel to do less work. I don't see why we should throw this away. Regards, Lucas -- Pengutronix e.K. | Lucas Stach | Industrial Linux Solutions | http://www.pengutronix.de/ | _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
