Mesa (master): i965: Skip register write detection when possible.
Kenneth Graunke
kwg at kemper.freedesktop.org
Mon Mar 20 23:01:28 UTC 2017
Module: Mesa
Branch: master
Commit: 5e29af5f772c1e1b02a4cc46d2f7d3b5d2151ad8
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=5e29af5f772c1e1b02a4cc46d2f7d3b5d2151ad8
Author: Kenneth Graunke <kenneth at whitecape.org>
Date: Thu Mar 2 18:27:32 2017 -0800
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 <kenneth at whitecape.org>
Reviewed-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
---
src/mesa/drivers/dri/i965/intel_screen.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 838151bf25..af9c9a45f3 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -1361,13 +1361,19 @@ err:
static bool
intel_detect_pipelined_so(struct intel_screen *screen)
{
+ const struct gen_device_info *devinfo = &screen->devinfo;
+
/* Supposedly, Broadwell just works. */
- if (screen->devinfo.gen >= 8)
+ if (devinfo->gen >= 8)
return true;
- if (screen->devinfo.gen <= 6)
+ if (devinfo->gen <= 6)
return false;
+ /* See the big explanation about command parser versions below */
+ if (screen->cmd_parser_version >= (devinfo->is_haswell ? 7 : 2))
+ return true;
+
/* We use SO_WRITE_OFFSET0 since you're supposed to write it (unlike the
* statistics registers), and we already reset it to zero before using it.
*/
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