On Wed, Jun 26, 2024 at 09:26:40AM GMT, Daniel Vetter wrote: > On Thu, May 09, 2024 at 05:41:18PM +0300, Oded Gabbay wrote: > > On Thu, May 09, 2024 at 03:53:01PM +0200, Tomeu Vizoso wrote: > > > Oded, Dave, > > > > > > Do you have an opinion on this? > > > > > > Thanks, > > > > > > Tomeu > > Hi Tomeu, > > > > Sorry for not replying earlier, I was down with Covid (again...). > > > > To your question, I don't have an objection to what you are > > suggesting. My personal view of accel is that it is an integral part of > > DRM and therefore, if there is an *existing* drm driver that wants to > > create an accel node, I'm not against it. > > Yeah, there's a continum from "clearly 3d gpu" to "compute AI > accelerator", with everything possible in-between shipping somewhere. > Collaboration is the important part, hair-splitting on where exactly the > driver should be is kinda secondary. I mean beyond "don't put a pure 3d > driver into accel or vice versa" of course :-) > > > There is the question of why you want to expose an accel node, and > > here I would like to hear Dave's and Sima's opinion on your suggested > > solution as it may affect the direction of other drm drivers. > > So existing userspace that blindly assumes that any render node will give > it useful 3d acceleration, then that's broken already. > > - kernel with new driver support but old mesa without that driver already > gives you that, even for a pure 3d chip. > > - intel (and I think also amd) have pure compute chips without 3d, so this > issue already exists > > Same for the other directions, 3d gpus have variable amounts of compute > chips nowadays. > > That leaves imo just the pragmatic choice, and if we need to complicate > the init flow of the kernel driver just for a different charnode major, > then I don't really see the point. > > And if we do see the point in this, I think the right approach would be if > we split the init flow further into allocating the drm_device, and then in > a 2nd step either allocate the accel or render uapi stuff as needed. The > DRIVER_FOO flags just aren't super flexible for this kinda of stuff and > have a bit a midlayer taste to them. Being able to defer render allocation would be extremely useful for MSM too as it's not currently possible to mask the driver_features during drm_dev_init() -- With best wishes Dmitry
