drm/i915/guc: Move check for fast memcpy_wc to relay creation

We only need those fast memcpy_wc when we're using relay to read
continuous GuC log. Let's prevent the user from creating a relay if we
know we won't be able to keep up with GuC.

v2: Adjust the return value (Michał)

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180319095348.9716-6-michal.winiarski@intel.com

diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
index 20254dde172cc5f3c86b3a38afe1d26c9766d37c..db89999a84e89f4f4e76c8bbdf5355cb68516e35 100644 (file)
--- a/drivers/gpu/drm/i915/intel_guc_log.c
+++ b/drivers/gpu/drm/i915/intel_guc_log.c
@@ -466,16 +466,6 @@ int intel_guc_log_create(struct intel_guc_log *log)
 
        GEM_BUG_ON(log->vma);
 
-       /*
-        * We require SSE 4.1 for fast reads from the GuC log buffer and
-        * it should be present on the chipsets supporting GuC based
-        * submisssions.
-        */
-       if (WARN_ON(!i915_has_memcpy_from_wc())) {
-               ret = -EINVAL;
-               goto err;
-       }
-
        vma = intel_guc_allocate_vma(guc, GUC_LOG_SIZE);
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
@@ -574,6 +564,16 @@ int intel_guc_log_relay_open(struct intel_guc_log *log)
                goto out_unlock;
        }
 
+       /*
+        * We require SSE 4.1 for fast reads from the GuC log buffer and
+        * it should be present on the chipsets supporting GuC based
+        * submisssions.
+        */
+       if (!i915_has_memcpy_from_wc()) {
+               ret = -ENXIO;
+               goto out_unlock;
+       }
+
        ret = guc_log_relay_create(log);
        if (ret)
                goto out_unlock;