From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Herrmann Subject: Re: [RFC 00/16] drm/nouveau: initial support for GK20A (Tegra K1) Date: Mon, 3 Feb 2014 12:25:00 +0100 Message-ID: References: <1391224618-3794-1-git-send-email-acourbot@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <1391224618-3794-1-git-send-email-acourbot@nvidia.com> Sender: linux-kernel-owner@vger.kernel.org To: Alexandre Courbot Cc: Ben Skeggs , nouveau@lists.freedesktop.org, "dri-devel@lists.freedesktop.org" , Alexandre Courbot , Eric Brower , Stephen Warren , linux-kernel , linux-tegra@vger.kernel.org, Terje Bergstrom , Ken Adams List-Id: linux-tegra@vger.kernel.org Hi [..snip..] > Finally, support for probing GK20A is added in the last 2 patches. It should be > noted that contrary to what Nouveau currently expects, GK20A does not embed any > display hardware (that part being handled by tegradrm). So this driver should > really be only used through DRM render-nodes and collaborate with the display > driver using PRIME. I have not yet figured out how to turn GK20A's instantiation > of Nouveau into a render-node only driver without breaking support for existing > desktop GPUs, and consequently the driver spawns a /dev/dri/cardX node which we > should try to get rid of. You cannot get rid of cardX currently. It is implied by DRIVER_MODESET and that flag should actually be called NOT_A_LEGACY_DRIVER. So you cannot remove it. I did try to replace DRIVER_MODESET by an inverted DRIVER_LEGACY flag some time ago, but I thought it's not worth it. Anyhow, you can easily add a new flag to make drm_dev_register()/drm_dev_alloc() not create the drm_minor for DRM_MINOR_LEGACY, which would prevent the card0 node from showing up. But people started using the cardX interface as base interface so mesa might not be able to open render-nodes if the related card-node is not available (which is a bug in their code, so no reason to support that by not adding stand-alone render-nodes). Long story short: If you want to do it properly, just add a flag to DRM core that prevents DRM_MINOR_LEGACY from showing up. If you just want it to work, simply keep a dummy card0. Thanks David