From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754128AbaIYSGk (ORCPT ); Thu, 25 Sep 2014 14:06:40 -0400 Received: from avon.wwwdotorg.org ([70.85.31.133]:33614 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754019AbaIYSGh (ORCPT ); Thu, 25 Sep 2014 14:06:37 -0400 Message-ID: <542459C5.9060505@wwwdotorg.org> Date: Thu, 25 Sep 2014 12:07:01 -0600 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.1.2 MIME-Version: 1.0 To: Thierry Reding CC: Sjoerd Simons , Alexandre Courbot , Ben Skeggs , nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org, gnurou@gmail.com Subject: Re: [5/5] ARM: tegra: jetson-tk1: enable GK20A GPU References: <1400491450-19223-6-git-send-email-acourbot@nvidia.com> <20140925132717.GA13579@dusk.luon.net> <54243931.6050804@wwwdotorg.org> <20140925164109.GA30382@ulmo> In-Reply-To: <20140925164109.GA30382@ulmo> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/25/2014 10:41 AM, Thierry Reding wrote: > On Thu, Sep 25, 2014 at 09:48:01AM -0600, Stephen Warren wrote: >> On 09/25/2014 07:27 AM, Sjoerd Simons wrote: >>> Playing a bit with todays linux-next on my jetson, it seems this patch is >>> still required for enabling the GPU. Is there anything blocking it (firmware >>> not available yet in liux-firmware?) >> >> I think initially I was waiting for the DRM patch "drm/nouvea: support for >> probing platform devices" to be applied, but it looks like that's been >> applied already, so only patches 4 and 5 in this series are still >> outstanding. >> >> Alex, wasn't there also some issue where the VPR register had to be >> programmed, and if it wasn't there'd be a hang when the GPU registers were >> touched? If we've added code to Nouveau/tegradrm to detect that and avoid >> the problem, then I guess we can commit these last two patches for 3.19. A >> resend after the 3.18 merge window might help. > > A patch that programs VPR was merged into U-Boot (though I don't think > it's made it into master yet). I'm not sure we can reasonably check for > that in Nouveau, given that the register is somewhere completely > unrelated. In fact I think the U-Boot patch was triggered by some > discussion about how to solve this and it was decided that it shouldn't > be done in the kernel, but U-Boot should set it up. > > That said, perhaps one solution would be to make U-Boot enable the gk20a > device if it's set up the VPR and disable it otherwise? For that to work, we'd need the DT to say status="disabled" by default for the GPU, and for the fixed U-Boot (and indeed every other bootloader...) to enable the GPU node. This would allow people with old versions of U-Boot (or other bootloaders) to continue to boot. This means bootloaders would only have to set status="okay", but never have to set status="disabled", which at least simplifies them a tiny bit.