i965: Store the GPU revision number in brw_context

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.

Reviewed-by: Kristian Høgsberg <[email protected]>

2 files changed, 23 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 88685cd8b6a..0d3af2cfb3d 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -658,6 +658,24 @@ 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,
@@ -716,6 +734,7 @@ 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 8b29e2ab4c8..e025011e2ae 100644
--- a/src/mesa/drivers/dri/i965/brw_context.h
+++ b/src/mesa/drivers/dri/i965/brw_context.h
@@ -1076,6 +1076,10 @@ 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;