Re: [Intel-gfx] [PATCH] drm/i915/dg2: make GuC FW a requirement for Gen12 and beyond devices

[Robert Beckett]

On 07/12/2021 23:15, John Harrison wrote:
On 12/7/2021 09:53, Adrian Larumbe wrote:
Beginning with DG2, all successive devices will require GuC FW to be
present and loaded at probe() time. This change alters error handling in
the FW init and load functions so that the driver's probe() function will
fail if GuC could not be loaded.
We still need to load the i915 driver in fall back mode (display but no 
engines) if the GuC is missing. Otherwise you may have just bricked the 
user's device.

good point, well made.
though this still seems like an issue for gen12+ (excluding rkl and adl).

maybe a redesign of toplevel driver probe, with i915_driver_early_probe 
before i915_driver_create could work. If the GuC fw is not found, it 
could then register a new kms only version of i915_drm_driver.

or something like like that ...


Also, we do want to be able to disable the GuC via the enable_guc module 
parameter.

John.


Signed-off-by: Adrian Larumbe <adrian.laru...@collabora.com>
---
  drivers/gpu/drm/i915/gt/uc/intel_uc.c | 20 ++++++++++++++++----
  drivers/gpu/drm/i915/gt/uc/intel_uc.h |  4 ++--
  drivers/gpu/drm/i915/i915_gem.c       |  7 ++++++-
  3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.c 
b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
index 7660eba893fa..8b0778b6d9ab 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.c
@@ -277,14 +277,19 @@ static void guc_disable_communication(struct 
intel_guc *guc)
      drm_dbg(&i915->drm, "GuC communication disabled\n");
  }
-static void __uc_fetch_firmwares(struct intel_uc *uc)
+static int __uc_fetch_firmwares(struct intel_uc *uc)
  {
+    struct drm_i915_private *i915 = uc_to_gt(uc)->i915;
      int err;
      GEM_BUG_ON(!intel_uc_wants_guc(uc));
      err = intel_uc_fw_fetch(&uc->guc.fw);
      if (err) {
+        /* GuC is mandatory on Gen12 and beyond */
+        if (GRAPHICS_VER(i915) >= 12)
+            return err;
+
          /* Make sure we transition out of transient "SELECTED" state */
          if (intel_uc_wants_huc(uc)) {
              drm_dbg(&uc_to_gt(uc)->i915->drm,
@@ -293,11 +298,13 @@ static void __uc_fetch_firmwares(struct intel_uc 
*uc)
                            INTEL_UC_FIRMWARE_ERROR);
          }
-        return;
+        return 0;
      }
      if (intel_uc_wants_huc(uc))
          intel_uc_fw_fetch(&uc->huc.fw);
+
+    return 0;
  }
  static void __uc_cleanup_firmwares(struct intel_uc *uc)
@@ -308,14 +315,19 @@ static void __uc_cleanup_firmwares(struct 
intel_uc *uc)
  static int __uc_init(struct intel_uc *uc)
  {
+    struct drm_i915_private *i915 = uc_to_gt(uc)->i915;
      struct intel_guc *guc = &uc->guc;
      struct intel_huc *huc = &uc->huc;
      int ret;
      GEM_BUG_ON(!intel_uc_wants_guc(uc));
-    if (!intel_uc_uses_guc(uc))
-        return 0;
+    if (!intel_uc_uses_guc(uc)) {
+        if (GRAPHICS_VER(i915) >= 12)
+            return -EINVAL;
+        else
+            return 0;
+    }
      if (i915_inject_probe_failure(uc_to_gt(uc)->i915))
          return -ENOMEM;
diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc.h 
b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
index 866b462821c0..3bcd781447bc 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_uc.h
+++ b/drivers/gpu/drm/i915/gt/uc/intel_uc.h
@@ -17,7 +17,7 @@ struct intel_uc;
  struct intel_uc_ops {
      int (*sanitize)(struct intel_uc *uc);
-    void (*init_fw)(struct intel_uc *uc);
+    int (*init_fw)(struct intel_uc *uc);
      void (*fini_fw)(struct intel_uc *uc);
      int (*init)(struct intel_uc *uc);
      void (*fini)(struct intel_uc *uc);
@@ -104,7 +104,7 @@ static inline _TYPE intel_uc_##_NAME(struct 
intel_uc *uc) \
      return _RET; \
  }
  intel_uc_ops_function(sanitize, sanitize, int, 0);
-intel_uc_ops_function(fetch_firmwares, init_fw, void, );
+intel_uc_ops_function(fetch_firmwares, init_fw, int, 0);
  intel_uc_ops_function(cleanup_firmwares, fini_fw, void, );
  intel_uc_ops_function(init, init, int, 0);
  intel_uc_ops_function(fini, fini, void, );
diff --git a/drivers/gpu/drm/i915/i915_gem.c 
b/drivers/gpu/drm/i915/i915_gem.c
index 527228d4da7e..7f8204af6826 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1049,7 +1049,12 @@ int i915_gem_init(struct drm_i915_private 
*dev_priv)
      if (ret)
          return ret;
-    intel_uc_fetch_firmwares(&dev_priv->gt.uc);
+    ret = intel_uc_fetch_firmwares(&dev_priv->gt.uc);
+    if (ret) {
+        i915_probe_error(dev_priv, "Failed to fetch firmware\n");
+        return ret;
+    }
+
      intel_wopcm_init(&dev_priv->wopcm);
      ret = i915_init_ggtt(dev_priv);