drm/i915/guc: add enable_guc_loading parameter

Split the function of "enable_guc_submission" into two separate
options.  The new one ("enable_guc_loading") controls only the
*fetching and loading* of the GuC firmware image. The existing
one is redefined to control only the *use* of the GuC for batch
submission once the firmware is loaded.

In addition, the degree of control has been refined from a simple
bool to an integer key, allowing several options:
-1 (default)     whatever the platform default is
 0  DISABLE      don't load/use the GuC
 1  BEST EFFORT  try to load/use the GuC, fallback if not available
 2  REQUIRE      must load/use the GuC, else leave the GPU wedged

The new platform default (as coded here) will be to attempt to
load the GuC iff the device has a GuC that requires firmware,
but not yet to use it for submission. A later patch will change
to enable it if appropriate.

v4:
    Changed some error-message levels, mostly ERROR->INFO, per
    review comments by Tvrtko Ursulin.

v5:
    Dropped one more error message, disabled GuC submission on
    hypothetical firmware-free devices [Tvrtko Ursulin].

v6:
    Logging tidy by Tvrtko Ursulin:
     * Do not log falling back to execlists when wedging the GPU.
     * Do not log fw load errors when load was disabled by user.
     * Pass down some error code from fw load for log message to
       make more sense.

Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (v5)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Tested-by: Fiedorowicz, Lukasz <lukasz.fiedorowicz@intel.com>
Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com> (v5)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Nick Hoath <nicholas.hoath@intel.com> (v6)

5 files changed, 89 insertions, 60 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 963f0318d4de..f78d4caf4b7f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4885,11 +4885,8 @@ i915_gem_init_hw(struct drm_device *dev)
         /* We can't enable contexts until all firmware is loaded */
         if (HAS_GUC(dev)) {
                 ret = intel_guc_setup(dev);
-                if (ret) {
-                        DRM_ERROR("Failed to initialize GuC, error %d\n", ret);
-                        ret = -EIO;
+                if (ret)
                         goto out;
-                }
         }
 
         /*
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 169242a8adff..916cd6778cf3 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -969,7 +969,7 @@ int intel_guc_suspend(struct drm_device *dev)
         struct intel_context *ctx;
         u32 data[3];
 
-        if (!i915.enable_guc_submission)
+        if (guc->guc_fw.guc_fw_load_status != GUC_FIRMWARE_SUCCESS)
                 return 0;
 
         ctx = dev_priv->kernel_context;
@@ -995,7 +995,7 @@ int intel_guc_resume(struct drm_device *dev)
         struct intel_context *ctx;
         u32 data[3];
 
-        if (!i915.enable_guc_submission)
+        if (guc->guc_fw.guc_fw_load_status != GUC_FIRMWARE_SUCCESS)
                 return 0;
 
         ctx = dev_priv->kernel_context;
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index cd74fb8e9387..21a323c01cdb 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -53,7 +53,8 @@ struct i915_params i915 __read_mostly = {
         .verbose_state_checks = 1,
         .nuclear_pageflip = 0,
         .edp_vswing = 0,
-        .enable_guc_submission = false,
+        .enable_guc_loading = -1,
+        .enable_guc_submission = 0,
         .guc_log_level = -1,
         .enable_dp_mst = true,
         .inject_load_failure = 0,
@@ -193,8 +194,15 @@ MODULE_PARM_DESC(edp_vswing,
                  "(0=use value from vbt [default], 1=low power swing(200mV),"
                  "2=default swing(400mV))");
 
-module_param_named_unsafe(enable_guc_submission, i915.enable_guc_submission, bool, 0400);
-MODULE_PARM_DESC(enable_guc_submission, "Enable GuC submission (default:false)");
+module_param_named_unsafe(enable_guc_loading, i915.enable_guc_loading, int, 0400);
+MODULE_PARM_DESC(enable_guc_loading,
+                "Enable GuC firmware loading "
+                "(-1=auto [default], 0=never, 1=if available, 2=required)");
+
+module_param_named_unsafe(enable_guc_submission, i915.enable_guc_submission, int, 0400);
+MODULE_PARM_DESC(enable_guc_submission,
+                "Enable GuC submission "
+                "(-1=auto, 0=never [default], 1=if available, 2=required)");
 
 module_param_named(guc_log_level, i915.guc_log_level, int, 0400);
 MODULE_PARM_DESC(guc_log_level,
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index dd0d0bbcc05b..658ce7379671 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -45,6 +45,8 @@ struct i915_params {
         int enable_ips;
         int invert_brightness;
         int enable_cmd_parser;
+        int enable_guc_loading;
+        int enable_guc_submission;
         int guc_log_level;
         int mmio_debug;
         int edp_vswing;
@@ -56,7 +58,6 @@ struct i915_params {
         bool load_detect_test;
         bool reset;
         bool disable_display;
-        bool enable_guc_submission;
         bool verbose_state_checks;
         bool nuclear_pageflip;
         bool enable_dp_mst;
diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
index 30ec8208dbbc..29273e5fee22 100644
--- a/drivers/gpu/drm/i915/intel_guc_loader.c
+++ b/drivers/gpu/drm/i915/intel_guc_loader.c
@@ -402,50 +402,42 @@ int intel_guc_setup(struct drm_device *dev)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
         struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
-        int retries, err = 0;
+        const char *fw_path = guc_fw->guc_fw_path;
+        int retries, ret, err;
 
-        if (!i915.enable_guc_submission)
-                return 0;
-
-        DRM_DEBUG_DRIVER("GuC fw status: fetch %s, load %s\n",
+        DRM_DEBUG_DRIVER("GuC fw status: path %s, fetch %s, load %s\n",
+                fw_path,
                 intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
                 intel_guc_fw_status_repr(guc_fw->guc_fw_load_status));
 
-        direct_interrupts_to_host(dev_priv);
-
-        if (guc_fw->guc_fw_fetch_status == GUC_FIRMWARE_NONE)
-                return 0;
-
-        if (guc_fw->guc_fw_fetch_status == GUC_FIRMWARE_SUCCESS &&
-            guc_fw->guc_fw_load_status == GUC_FIRMWARE_FAIL)
-                return -ENOEXEC;
-
-        guc_fw->guc_fw_load_status = GUC_FIRMWARE_PENDING;
-
-        DRM_DEBUG_DRIVER("GuC fw fetch status %s\n",
-                intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status));
+        /* Loading forbidden, or no firmware to load? */
+        if (!i915.enable_guc_loading) {
+                err = 0;
+                goto fail;
+        } else if (fw_path == NULL || *fw_path == '\0') {
+                if (*fw_path == '\0')
+                        DRM_INFO("No GuC firmware known for this platform\n");
+                err = -ENODEV;
+                goto fail;
+        }
 
-        switch (guc_fw->guc_fw_fetch_status) {
-        case GUC_FIRMWARE_FAIL:
-                /* something went wrong :( */
+        /* Fetch failed, or already fetched but failed to load? */
+        if (guc_fw->guc_fw_fetch_status != GUC_FIRMWARE_SUCCESS) {
                 err = -EIO;
                 goto fail;
-
-        case GUC_FIRMWARE_NONE:
-        case GUC_FIRMWARE_PENDING:
-        default:
-                /* "can't happen" */
-                WARN_ONCE(1, "GuC fw %s invalid guc_fw_fetch_status %s [%d]\n",
-                        guc_fw->guc_fw_path,
-                        intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
-                        guc_fw->guc_fw_fetch_status);
-                err = -ENXIO;
+        } else if (guc_fw->guc_fw_load_status == GUC_FIRMWARE_FAIL) {
+                err = -ENOEXEC;
                 goto fail;
-
-        case GUC_FIRMWARE_SUCCESS:
-                break;
         }
 
+        direct_interrupts_to_host(dev_priv);
+
+        guc_fw->guc_fw_load_status = GUC_FIRMWARE_PENDING;
+
+        DRM_DEBUG_DRIVER("GuC fw status: fetch %s, load %s\n",
+                intel_guc_fw_status_repr(guc_fw->guc_fw_fetch_status),
+                intel_guc_fw_status_repr(guc_fw->guc_fw_load_status));
+
         err = i915_guc_submission_init(dev);
         if (err)
                 goto fail;
@@ -463,7 +455,7 @@ int intel_guc_setup(struct drm_device *dev)
                  */
                 err = i915_reset_guc(dev_priv);
                 if (err) {
-                        DRM_ERROR("GuC reset failed, err %d\n", err);
+                        DRM_ERROR("GuC reset failed: %d\n", err);
                         goto fail;
                 }
 
@@ -474,8 +466,8 @@ int intel_guc_setup(struct drm_device *dev)
                 if (--retries == 0)
                         goto fail;
 
-                DRM_INFO("GuC fw load failed, err %d; will reset and "
-                        "retry %d more time(s)\n", err, retries);
+                DRM_INFO("GuC fw load failed: %d; will reset and "
+                         "retry %d more time(s)\n", err, retries);
         }
 
         guc_fw->guc_fw_load_status = GUC_FIRMWARE_SUCCESS;
@@ -497,7 +489,6 @@ int intel_guc_setup(struct drm_device *dev)
         return 0;
 
 fail:
-        DRM_ERROR("GuC firmware load failed, err %d\n", err);
         if (guc_fw->guc_fw_load_status == GUC_FIRMWARE_PENDING)
                 guc_fw->guc_fw_load_status = GUC_FIRMWARE_FAIL;
 
@@ -505,7 +496,41 @@ fail:
         i915_guc_submission_disable(dev);
         i915_guc_submission_fini(dev);
 
-        return err;
+        /*
+         * We've failed to load the firmware :(
+         *
+         * Decide whether to disable GuC submission and fall back to
+         * execlist mode, and whether to hide the error by returning
+         * zero or to return -EIO, which the caller will treat as a
+         * nonfatal error (i.e. it doesn't prevent driver load, but
+         * marks the GPU as wedged until reset).
+         */
+        if (i915.enable_guc_loading > 1) {
+                ret = -EIO;
+        } else if (i915.enable_guc_submission > 1) {
+                ret = -EIO;
+        } else {
+                ret = 0;
+        }
+
+        if (err == 0)
+                DRM_INFO("GuC firmware load skipped\n");
+        else if (ret == -EIO)
+                DRM_ERROR("GuC firmware load failed: %d\n", err);
+        else
+                DRM_INFO("GuC firmware load failed: %d\n", err);
+
+        if (i915.enable_guc_submission) {
+                if (fw_path == NULL)
+                        DRM_INFO("GuC submission without firmware not supported\n");
+                if (ret == 0)
+                        DRM_INFO("Falling back to execlist mode\n");
+                else
+                        DRM_ERROR("GuC init failed: %d\n", ret);
+        }
+        i915.enable_guc_submission = 0;
+
+        return ret;
 }
 
 static void guc_fw_fetch(struct drm_device *dev, struct intel_guc_fw *guc_fw)
@@ -644,8 +669,11 @@ void intel_guc_init(struct drm_device *dev)
         struct intel_guc_fw *guc_fw = &dev_priv->guc.guc_fw;
         const char *fw_path;
 
-        if (!HAS_GUC_SCHED(dev))
-                i915.enable_guc_submission = false;
+        /* A negative value means "use platform default" */
+        if (i915.enable_guc_loading < 0)
+                i915.enable_guc_loading = HAS_GUC_UCODE(dev);
+        if (i915.enable_guc_submission < 0)
+                i915.enable_guc_submission = HAS_GUC_SCHED(dev);
 
         if (!HAS_GUC_UCODE(dev)) {
                 fw_path = NULL;
@@ -658,26 +686,21 @@ void intel_guc_init(struct drm_device *dev)
                 guc_fw->guc_fw_major_wanted = 8;
                 guc_fw->guc_fw_minor_wanted = 7;
         } else {
-                i915.enable_guc_submission = false;
                 fw_path = "";   /* unknown device */
         }
 
-        if (!i915.enable_guc_submission)
-                return;
-
         guc_fw->guc_dev = dev;
         guc_fw->guc_fw_path = fw_path;
         guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_NONE;
         guc_fw->guc_fw_load_status = GUC_FIRMWARE_NONE;
 
+        /* Early (and silent) return if GuC loading is disabled */
+        if (!i915.enable_guc_loading)
+                return;
         if (fw_path == NULL)
                 return;
-
-        if (*fw_path == '\0') {
-                DRM_ERROR("No GuC firmware known for this platform\n");
-                guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_FAIL;
+        if (*fw_path == '\0')
                 return;
-        }
 
         guc_fw->guc_fw_fetch_status = GUC_FIRMWARE_PENDING;
         DRM_DEBUG_DRIVER("GuC firmware pending, path %s\n", fw_path);