On Thu, Jun 16, 2016 at 01:09:34PM +0100, Jose Abreu wrote: > Hi Daniel, > > Sorry to bother you again. I promise this is the last time :) > > On 15-06-2016 11:15, Daniel Vetter wrote: > > On Wed, Jun 15, 2016 at 11:48 AM, Jose Abreu <Jose.Abreu@xxxxxxxxxxxx> wrote: > >> On 15-06-2016 09:52, Daniel Vetter wrote: > >>> On Tue, Jun 14, 2016 at 1:19 PM, Jose Abreu <Jose.Abreu@xxxxxxxxxxxx> wrote: > >>>>> I assume that xilinx VDMA is the only way to feed pixel data into your > >>>>> display pipeline. Under that assumption: > >>>>> > >>>>> drm_plane should map to Xilinx VDMA, and the drm_plane->drm_crtc link > >>>>> would represent the dma channel. With atomic you can subclass > >>>>> drm_plane/crtc_state structures to store all the runtime configuration in > >>>>> there. > >>>>> > >>>>> The actual buffer itsel would be represented by a drm_framebuffer, which > >>>>> either wraps a shmem gem or a cma gem object. > >>>>> > >>>>> If you want to know about the callbacks used by the atomic helpers to push > >>>>> out plane updates, look at the hooks drm_atomic_helper_commit_planes() > >>>>> (and the related functions, see kerneldoc) calls. > >>>>> > >>>>> I hope this helps a bit more. > >>>>> -Daniel > >>>> Thanks a lot! With your help I was able to implement all the > >>>> needed logic. Sorry to bother you but I have one more question. > >>>> Right now I can initialize and configure the vdma correctly but I > >>>> can only send one frame. I guess when the dma completes > >>>> transmission I need to ask drm for a new frame, right? Because > >>>> the commit function starts the vdma correctly but then the dma > >>>> halts waiting for a new descriptor. > >>> DRM has a continuous scanout model, i.e. when userspace doesn't give > >>> you a new frame you're supposed to keep scanning out the current one. > >>> So you need to rearm your upload code with the same drm_framebuffer if > >>> userspace hasn't supplied a new one since the last time before the > >>> vblank period starts. > >>> > >>> This is different to v4l, where userspace has to supply each frame > >>> (and the kernel gets angry when there's not enough frames and signals > >>> an underrun of the queue). This is because drm is geared at desktops, > >>> and there it's perfectly normal to show the exact same frame for a > >>> long time. > >>> -Daniel > >> Thanks, I was thinking this was similar to v4l. I am now able to > >> send multiple frames so it is finally working! I have one little > >> implementation detail: The controller that I am using supports > >> deep color mode but I am using FB CMA helpers to create the > >> framebuffer and I've seen that the supported bpp in these helpers > >> only goes up to 32, right? Does this means that with these > >> helpers I can't use deep color? Can I implement this deep color > >> mode (48bpp) using a custom fb or do I also need custom gem > >> allocation functions (Right now I am using GEM CMA helpers)? > > Suprising the cma doesn't take pixel_format into account. If this > > really doesn't work, pls fix up the cma helpers, not roll your own > > copypasta ;-) > > > > Note that the fbdev emulation itself (maybe that's what threw you off) > > only supports legacy rgb formats up to 32bits. But native kms can > > support anything, we just might need to add the DRM_FOURCC codes for > > that. > > -Daniel > > So, I ended up using 32bits and everything is working fine! I > tested using [1] and [2] but now I have kind of a dumb question: > I want to use the new driver that I created as a secondary output > of my desktop so that I can play videos using mplayer but I am > not being able to do this. If I check in my linux settings only > one display is being detected, although in /dev/dri the two video > cards are present (the native one and the one I added). Does the > driver needs something additional to do this or is it only in my > X configuration? I tried editing this configuration but still > doesn't work. I believe that because my driver is not being > probed at runtime the display is not being created by X. Is this > correct? X with multiple drivers is kinda a bit much. I think it should work somewhat if you treat the 2nd driver as an offload engine. Afaik you can change that through xrandr, but not sure. I didn't implement this. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
