From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michel =?ISO-8859-1?Q?D=E4nzer?= Date: Tue, 16 Mar 2010 13:46:26 +0000 Subject: Re: [Linux-fbdev-devel] drm_fb_helper: Impossible to change video Message-Id: <1268747186.4176.38.camel@thor.local> List-Id: References: <1268302426.7444.117.camel@thor.local> <21d7e9971003121251v4bef7e96v67f3d98aa9ab384a@mail.gmail.com> <21d7e9971003131301r723f3311p3553ea8a1a86bf0a@mail.gmail.com> <1268566880.9302.65.camel@thor.local> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: James Simmons Cc: Linux Fbdev development list , Paulius Zaleckas , Michal Suchanek , Alex Deucher , DRI development list On Mon, 2010-03-15 at 18:38 +0000, James Simmons wrote:=20 > > > The big issue we have with resizing the buffer is userspace mmaps of = the fbdev > > > device, and invalidation. > > > Previous thread of unresolvedness is here. > > > http://www.mail-archive.com/dri-devel@lists.sourceforge.net/msg41878.= html > >=20 > > Actually AFAIR (and reading through it again seems to confirm this) > > userspace mappings should be fully handled by the last patch series I > > posted back then[0]. The problem was that the struct fb_ops hooks may be > > called by the kernel from pretty much any context, and neither I nor > > Thomas was sure how to handle the TTM locking given that. Maybe James > > has ideas for this given his better familiarity with fbdev internals. >=20 > The fb_ops can only be called from fbcon or the fbdev userland interface.= =20 > The fbcon calls should only happen when the VC is in KD_TEXT mode. Now=20 > with the DRM backend we have the advantage of creating a mapping seperate= =20 > from the console mapping. A fb_open/fb_close could be used to cleaning up= =20 > the userland mmap as well as handle the console pinning. We can supply=20 > your own fb_mmap hook. Again, the issue is not userspace but that fb_ops hooks can be called from interrupt context etc. --=20 Earthling Michel D=C3=A4nzer | http://www.vmware.c= om Libre software enthusiast | Debian, X and DRI developer