[Mesa-dev] [PATCH 1/5] i965: Query and store GPU properties from kernel

[Ben Widawsky]

Certain products are not uniquely identifiable based on device id alone. The
kernel exports an interface to help deal with this. This patch merely introduces
the consumer of the interface and makes sure nothing breaks.

It is also possible to use these values for programming GPGPU mode, and I plan
to do that as well.

The interface was introduced in libdrm 2.4.60, which is already required, so it
should all be fine.

Signed-off-by: Ben Widawsky <benjamin.widawsky at intel.com>
---
 src/mesa/drivers/dri/i965/intel_screen.c | 21 +++++++++++++++++++++
 src/mesa/drivers/dri/i965/intel_screen.h | 12 +++++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index ee7c1d7..343b497 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -1082,6 +1082,7 @@ static bool
 intel_init_bufmgr(struct intel_screen *intelScreen)
 {
    __DRIscreen *spriv = intelScreen->driScrnPriv;
+   bool devid_override = getenv("INTEL_DEVID_OVERRIDE") != NULL;
 
    intelScreen->no_hw = getenv("INTEL_NO_HW") != NULL;
 
@@ -1099,6 +1100,26 @@ intel_init_bufmgr(struct intel_screen *intelScreen)
       return false;
    }
 
+   intelScreen->subslice_total = -1;
+   intelScreen->eu_total = -1;
+
+   /* Everything below this is for real hardware only */
+   if (intelScreen->no_hw || devid_override)
+      return true;
+
+   intel_get_param(spriv, I915_PARAM_SUBSLICE_TOTAL,
+                   &intelScreen->subslice_total);
+   intel_get_param(spriv, I915_PARAM_EU_TOTAL, &intelScreen->eu_total);
+
+   /* Without this information, we cannot get the right Braswell brandstrings,
+    * and we have to use conservative numbers for GPGPU on many platforms, but
+    * otherwise, things will just work.
+    */
+   if (intelScreen->subslice_total == -1 ||
+       intelScreen->eu_total == -1)
+      _mesa_warning(NULL,
+                    "Kernel 4.1 required to properly query GPU properties.\n");
+
    return true;
 }
 
diff --git a/src/mesa/drivers/dri/i965/intel_screen.h b/src/mesa/drivers/dri/i965/intel_screen.h
index 3a5f22c..695ed50 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.h
+++ b/src/mesa/drivers/dri/i965/intel_screen.h
@@ -81,7 +81,17 @@ struct intel_screen
     * I915_PARAM_CMD_PARSER_VERSION parameter
     */
    int cmd_parser_version;
- };
+
+   /**
+    * Best effort attempt to get system information. Needed for GPGPU, and brand
+    * strings (sigh)
+    * I915_PARAM_SUBSLICE_TOTAL, and I915_PARAM_EU_TOTAL
+    */
+   struct {
+      int subslice_total;
+      int eu_total;
+   };
+};
 
 extern void intelDestroyContext(__DRIcontext * driContextPriv);
 
-- 
2.7.1