Hi, On Mon, 2018-08-20 at 11:56 +0200, Maxime Ripard wrote: > On Tue, Aug 07, 2018 at 10:31:30PM +0200, Paul Kocialkowski wrote: > > Hi, > > > > Le mardi 07 août 2018 à 22:18 +0200, Daniel Vetter a écrit : > > > On Tue, Aug 07, 2018 at 09:39:19PM +0200, Paul Kocialkowski wrote: > > > > Initializing and registering fbdev requires at least one DRM connector > > > > and will fail otherwise. In order to support headless setups (for > > > > instance for GPU rendering with the GBM backend, where a DRI card node > > > > is required to provide GEM memory reservation), add a check on the > > > > number of registered connectors before initializing fbdev. > > > > > > sun4i is a pure kms driver, why exactly do you need it for gbm backed > > > rendering? What exactly is rendering here, and why does it insist on a > > > display card node, even if that display card node is 100% defunct? > > > > The non-free Mali blobs provide GPU support with a GBM interface that > > takes a DRM fd in order to reserve the memory it needs for its rendering > > targets. This uses the GEM interface available through the DRI card node > > (and there is no render node with the non-free Mali driver). Allwinner > > has a minimalistic out-of-tree driver pretty much only for this purpose. > > > > I crafted this patch when someone on IRC tried to get the out-of-tree > > Mali GPU driver going with the mainline kernel in order to do rendering > > in a GBM buffer, since it's apparently the only option for headless > > rendering with the blob. > > > > In my opinion, supporting the pipeline of an out-of-tree GPU driver that > > only works with a non-free userspace blob is not a valid reason to do > > anything. Still, it felt like adding support for the headless use-case > > wouldn't hurt, whatever the underlying use case for it may be. > > If you start considering the DMA constraints and the API in itself, it > does hurt. You'll get buffers that are not meant for the GPU, and > might not be accessible, and from another device without using > dma-buf, which again works because the hardware is dumb enough, but is > breaking a lot of expectations in the process. You're right, this is too much abuse. I'm dropping this patch then. Cheers, Paul > If one wants to do headless rendering, mali-drm or lima looks like a > better solution. > > Maxime > -- Developer of free digital technology and hardware support. Website: https://www.paulk.fr/ Coding blog: https://code.paulk.fr/ Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/ _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
