From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: rfc: breaking old userspace gamma for 10-bit support Date: Fri, 23 Jul 2010 13:13:48 -0700 Message-ID: <87pqyeklc3.fsf@pollan.anholt.net> References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1018694246==" Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Andrew Lutomirski , intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org --===============1018694246== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha1; protocol="application/pgp-signature" --=-=-= Content-Transfer-Encoding: quoted-printable On Fri, 23 Jul 2010 14:00:30 -0400, Andrew Lutomirski wrote: > AFAICT intel hardware wants a 129-entry LUT when using high precision > gamma ramps. Rather than hacking some kind of decimation into the > kernel driver (and thus silently breaking DirectColor), I'd like to > teach userspace how to deal with variable gamma sizes. >=20 > gnome-color-manager already more-or-less supports arbitrary gamma ramp > sizes (supposedly), dispwin ought to do it, and there might not be any > other software that really cares. gnome-screensaver saves and > restores the gamma ramp, and I haven't checked if it works right for > funny sizes. >=20 > The worst problem we'll have is that current xf86-drv-intel can't > handle non-256 gamma sizes at all. So if we change the kernel we'll > break it completely. >=20 > One option is to have the kernel report gamma_size =3D 129 but still > accept 256 and decimate itself. That might cause current userspace to > keep working (except for DirectColor). >=20 > Any thoughts? The kernel doesn't get to break old userspace. The kernel could support new userspace that only asks for 129 slots and set a mode that has better precision in that case. New interfaces would probably be required to communicate that up front -- I haven't looked into it, but I just want to make sure you don't spend a bunch of time going down a path that will be rejected. --=-=-= Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) iEYEARECAAYFAkxJ9/wACgkQHUdvYGzw6vcg/ACdGU1KCpmWd4ffvlTU5UyNDB+d YusAniWqQLCY4u8Xw5KRp4ooNkgP/W0i =88PG -----END PGP SIGNATURE----- --=-=-=-- --===============1018694246== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx --===============1018694246==--