i965: Skip register write detection when possible.
Detecting register write support by trial and error introduces a
stall at screen creation time, which it would be nice to avoid.
Certain command parser versions guarantee this will work (see the
giant comment in intelInitScreen2 below, or a few commits ago):
- Ivybridge: version >= 1 (kernel v3.16)
- Baytrail: version >= 2 (kernel v3.19)
- Haswell: version >= 7 (kernel v4.8)
For simplicity, we don't bother with version 1 in this patch.
This assumes that the user hasn't disabled aliasing PPGTT via a kernel
command line parameter. Don't do that - you're only breaking things.
Signed-off-by: Kenneth Graunke <email@example.com>
Reviewed-by: Samuel Iglesias Gonsálvez <firstname.lastname@example.org>
(cherry picked from commit 5e29af5f772c1e1b02a4cc46d2f7d3b5d2151ad8)
1 file changed