From 5e29af5f772c1e1b02a4cc46d2f7d3b5d2151ad8 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Thu, 2 Mar 2017 18:27:32 -0800 Subject: [PATCH] i965: Skip register write detection when possible. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Samuel Iglesias Gonsálvez --- 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 838151b..af9c9a4 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. */ -- 2.7.4