From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S933232AbbI2Id0 (ORCPT <rfc822;w@1wt.eu>);
	Tue, 29 Sep 2015 04:33:26 -0400
Received: from galahad.ideasonboard.com ([185.26.127.97]:41545 "EHLO
	galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S932836AbbI2IdW (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 29 Sep 2015 04:33:22 -0400
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>, David Herrmann <dh.herrmann@gmail.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Thomas Petazzoni <thomas.petazzoni@free-electrons.com>,
        linux-fbdev <linux-fbdev@vger.kernel.org>,
        Teddy Wang <teddy.wang@siliconmotion.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Arnaud Patard <apatard@mandriva.com>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Dave Airlie <airlied@redhat.com>,
        Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Subject: Re: No more new fbdev drivers, please
Date: Tue, 29 Sep 2015 11:33:27 +0300
Message-ID: <3297297.aAyMzK5j4J@avalon>
User-Agent: KMail/4.14.8 (Linux/4.0.5-gentoo; KDE/4.14.8; x86_64; ; )
In-Reply-To: <1443515003.21557.12.camel@redhat.com>
References: <5603EC15.9090605@ti.com> <20150928123627.GD3383@phenom.ffwll.local> <1443515003.21557.12.camel@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 7Bit
Content-Type: text/plain; charset="us-ascii"
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Gerd,

On Tuesday 29 September 2015 10:23:23 Gerd Hoffmann wrote:
> On Mo, 2015-09-28 at 14:36 +0200, Daniel Vetter wrote:
> > On Mon, Sep 28, 2015 at 09:39:13AM +0200, Gerd Hoffmann wrote:
> > >   Hi,
> > >   
> > > > As Daniel mentioned, the connector+encoder+crtc combination is one of
> > > > those simplifications that would make sense if more such drivers are
> > > > added.
> > > 
> > > Another one is memory management.  It's pretty complex because it can
> > > handle _way_ more than what simple drivers need, and the result is
> > > _alot_ of ttm boilerplate in the drivers.
> > 
> > ttm is pretty impressive overkill for most simplistic drm drivers. If you
> > just need contiguous framebuffers for display then the cma helpers should
> > take care of pretty much all the boilerplate for you. They have ready-made
> > simple gem and dumb framebuffer mmap support, which is all a basic kms
> > driver needs.
> 
> Does that work on !arm meanwhile?  Last time I checked (when writing
> bochsdrm, around v3.14) the cma helpers didn't even build on x86 ...

config DRM_GEM_CMA_HELPER
        bool
        depends on DRM && HAVE_DMA_ATTRS
        help
          Choose this if you need the GEM CMA helper functions

x86 defines HAVE_DMA_ATTRS.

-- 
Regards,

Laurent Pinchart