[Intel-xe] [PATCH v2 3/3] drm/xe/uc: Add GuC/HuC firmware path overrides

[Daniele Ceraolo Spurio]

When testing a new binary and/or debugging binary-related issues, it is
useful to have the option to change which binary is loaded without
having to update and re-compile the kernel. To support this option, this
patch adds 2 new modparams to override the FW path for GuC and HuC. The
HuC modparam can also be set to an empty string to disable HuC loading.

Note that those modparams only take effect on platforms where we already
have a default FW, so we're sure there is support for FW loading and the
kernel isn't going to explode in an undefined path.

v2: simplify comment (John),
    rebase on s/guc_submission_enabled/uc_enabled

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: John Harrison <John.C.Harrison at Intel.com>
Cc: Matthew Brost <matthew.brost at intel.com>
Reviewed-by: John Harrison <John.C.Harrison at Intel.com>
---
 drivers/gpu/drm/xe/xe_module.c | 10 ++++++++++
 drivers/gpu/drm/xe/xe_module.h |  2 ++
 drivers/gpu/drm/xe/xe_uc_fw.c  | 30 +++++++++++++++++++++++++++++-
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_module.c b/drivers/gpu/drm/xe/xe_module.c
index de85494e2280..0660017c3e83 100644
--- a/drivers/gpu/drm/xe/xe_module.c
+++ b/drivers/gpu/drm/xe/xe_module.c
@@ -30,6 +30,16 @@ int xe_guc_log_level = 5;
 module_param_named(guc_log_level, xe_guc_log_level, int, 0600);
 MODULE_PARM_DESC(guc_log_level, "GuC firmware logging level (0=disable, 1..5=enable with verbosity min..max)");
 
+char *xe_guc_firmware_path = NULL;
+module_param_named_unsafe(guc_firmware_path, xe_guc_firmware_path, charp, 0400);
+MODULE_PARM_DESC(guc_firmware_path,
+		 "GuC firmware path to use instead of the default one");
+
+char *xe_huc_firmware_path = NULL;
+module_param_named_unsafe(huc_firmware_path, xe_huc_firmware_path, charp, 0400);
+MODULE_PARM_DESC(huc_firmware_path,
+		 "HuC firmware path to use instead of the default one - empty string disables");
+
 char *xe_param_force_probe = CONFIG_DRM_XE_FORCE_PROBE;
 module_param_named_unsafe(force_probe, xe_param_force_probe, charp, 0400);
 MODULE_PARM_DESC(force_probe,
diff --git a/drivers/gpu/drm/xe/xe_module.h b/drivers/gpu/drm/xe/xe_module.h
index 2c1f9199f909..e1da1e9ca5cb 100644
--- a/drivers/gpu/drm/xe/xe_module.h
+++ b/drivers/gpu/drm/xe/xe_module.h
@@ -10,4 +10,6 @@ extern bool force_execlist;
 extern bool enable_display;
 extern u32 xe_force_vram_bar_size;
 extern int xe_guc_log_level;
+extern char *xe_guc_firmware_path;
+extern char *xe_huc_firmware_path;
 extern char *xe_param_force_probe;
diff --git a/drivers/gpu/drm/xe/xe_uc_fw.c b/drivers/gpu/drm/xe/xe_uc_fw.c
index 015af1e20490..c0f1698cc05a 100644
--- a/drivers/gpu/drm/xe/xe_uc_fw.c
+++ b/drivers/gpu/drm/xe/xe_uc_fw.c
@@ -15,6 +15,7 @@
 #include "xe_gt.h"
 #include "xe_map.h"
 #include "xe_mmio.h"
+#include "xe_module.h"
 #include "xe_uc_fw.h"
 
 /*
@@ -210,6 +211,30 @@ uc_fw_auto_select(struct xe_device *xe, struct xe_uc_fw *uc_fw)
 	}
 }
 
+static void
+uc_fw_override(struct xe_uc_fw *uc_fw)
+{
+	char *path_override = NULL;
+
+	/* empty string disables, but it's not allowed for GuC */
+	switch (uc_fw->type) {
+	case XE_UC_FW_TYPE_GUC:
+		if (xe_guc_firmware_path && *xe_guc_firmware_path)
+			path_override = xe_guc_firmware_path;
+		break;
+	case XE_UC_FW_TYPE_HUC:
+		path_override = xe_huc_firmware_path;
+		break;
+	default:
+		break;
+	}
+
+	if (path_override) {
+		uc_fw->path = path_override;
+		uc_fw->user_overridden = true;
+	}
+}
+
 /**
  * xe_uc_fw_copy_rsa - copy fw RSA to buffer
  *
@@ -347,7 +372,10 @@ int xe_uc_fw_init(struct xe_uc_fw *uc_fw)
 	if (!xe_uc_fw_is_supported(uc_fw))
 		return 0;
 
-	if (!xe_device_uc_enabled(xe)) {
+	uc_fw_override(uc_fw);
+
+	/* an empty path means the firmware is disabled */
+	if (!xe_device_uc_enabled(xe) || !(*uc_fw->path)) {
 		xe_uc_fw_change_status(uc_fw, XE_UC_FIRMWARE_DISABLED);
 		drm_dbg(&xe->drm, "%s disabled", xe_uc_fw_type_repr(uc_fw->type));
 		return 0;
-- 
2.41.0