[Mesa-dev] [PATCH 1/2] i965: Store the GPU revision number in brw_context

[Neil Roberts]

brwContextInit now queries the GPU revision number via a new parameter
for DRM_I915_GETPARAM. This new parameter requires a kernel patch and
a patch to libdrm. If the kernel doesn't support it then it will
continue but set the revision number to -1. The intention is to use
this to implement workarounds that are only needed on certain
steppings of the GPU.
---
 configure.ac                            |  2 +-
 src/mesa/drivers/dri/i965/brw_context.c | 19 +++++++++++++++++++
 src/mesa/drivers/dri/i965/brw_context.h |  4 ++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index c5abbfd..23ac927 100644
--- a/configure.ac
+++ b/configure.ac
@@ -61,7 +61,7 @@ AC_SUBST([OSMESA_VERSION])
 dnl Versions for external dependencies
 LIBDRM_REQUIRED=2.4.38
 LIBDRM_RADEON_REQUIRED=2.4.56
-LIBDRM_INTEL_REQUIRED=2.4.52
+LIBDRM_INTEL_REQUIRED=2.4.59
 LIBDRM_NVVIEUX_REQUIRED=2.4.33
 LIBDRM_NOUVEAU_REQUIRED="2.4.33 libdrm >= 2.4.41"
 LIBDRM_FREEDRENO_REQUIRED=2.4.57
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 786e6f5..18f72d8 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -651,6 +651,24 @@ brw_process_driconf_options(struct brw_context *brw)
       driQueryOptionb(options, "allow_glsl_extension_directive_midshader");
 }
 
+static int
+brw_get_revision(int fd)
+{
+   struct drm_i915_getparam gp;
+   int revision;
+   int ret;
+
+   memset(&gp, 0, sizeof(gp));
+   gp.param = I915_PARAM_REVISION;
+   gp.value = &revision;
+
+   ret = drmCommandWriteRead(fd, DRM_I915_GETPARAM, &gp, sizeof(gp));
+   if (ret)
+      revision = -1;
+
+   return revision;
+}
+
 GLboolean
 brwCreateContext(gl_api api,
 	         const struct gl_config *mesaVis,
@@ -709,6 +727,7 @@ brwCreateContext(gl_api api,
    brw->has_negative_rhw_bug = devinfo->has_negative_rhw_bug;
    brw->needs_unlit_centroid_workaround =
       devinfo->needs_unlit_centroid_workaround;
+   brw->revision = brw_get_revision(sPriv->fd);
 
    brw->must_use_separate_stencil = screen->hw_must_use_separate_stencil;
    brw->has_swizzling = screen->hw_has_swizzling;
diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
index 682fbe9..10e8274 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -1064,6 +1064,10 @@ struct brw_context
 
    int gen;
    int gt;
+   /* GT revision. This will be -1 if the revision couldn't be determined (eg,
+    * if the kernel doesn't support the query).
+    */
+   int revision;
 
    bool is_g4x;
    bool is_baytrail;
-- 
1.9.3