[PATCH 15/15] drm/xe: Add enable_media module parameter

[Stuart Summers <stuart.summers@intel.com>]

The gt_types_allowed configfs attribute is debug-only, so provide a
supported way to disable the media GT on production builds. The
modparam takes precedence over configfs so a single knob is enough to
guarantee the media GT is left alone.

Signed-off-by: Stuart Summers <stuart.summers@intel.com>
Assisted-by: LLM
---
 drivers/gpu/drm/xe/xe_configfs_debug.c |  3 +++
 drivers/gpu/drm/xe/xe_defaults.h       |  1 +
 drivers/gpu/drm/xe/xe_module.c         |  6 ++++++
 drivers/gpu/drm/xe/xe_module.h         |  1 +
 drivers/gpu/drm/xe/xe_pci.c            | 19 ++++++++++++++++---
 5 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_configfs_debug.c b/drivers/gpu/drm/xe/xe_configfs_debug.c
index aa8b73cb2a64..e6a0b1f960bc 100644
--- a/drivers/gpu/drm/xe/xe_configfs_debug.c
+++ b/drivers/gpu/drm/xe/xe_configfs_debug.c
@@ -184,6 +184,9 @@
  * will always return one GT type per line. "primary" and "media" are the
  * GT type names supported by this interface.
  *
+ * Note that the ``enable_media=0`` module parameter takes precedence over
+ * this attribute: it disables the media GT even if "media" is listed here.
+ *
  * This attribute can only be set before binding to the device.
  *
  * Examples:
diff --git a/drivers/gpu/drm/xe/xe_defaults.h b/drivers/gpu/drm/xe/xe_defaults.h
index 20292e682bf9..fdb12ebfa4e4 100644
--- a/drivers/gpu/drm/xe/xe_defaults.h
+++ b/drivers/gpu/drm/xe/xe_defaults.h
@@ -18,6 +18,7 @@
 /* Sentinel value for guc_log_level configfs: not set, fall back to module param */
 #define XE_GUC_LOG_LEVEL_UNSET			-1
 
+#define XE_DEFAULT_ENABLE_MEDIA			true
 #define XE_DEFAULT_PROBE_DISPLAY		IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
 #define XE_DEFAULT_VRAM_BAR_SIZE		0
 #define XE_DEFAULT_FORCE_PROBE			CONFIG_DRM_XE_FORCE_PROBE
diff --git a/drivers/gpu/drm/xe/xe_module.c b/drivers/gpu/drm/xe/xe_module.c
index 897724cb5cfb..be6a3a439cb0 100644
--- a/drivers/gpu/drm/xe/xe_module.c
+++ b/drivers/gpu/drm/xe/xe_module.c
@@ -22,6 +22,7 @@
 #include "xe_sched_job.h"
 
 struct xe_modparam xe_modparam = {
+	.enable_media =		XE_DEFAULT_ENABLE_MEDIA,
 	.probe_display =	XE_DEFAULT_PROBE_DISPLAY,
 	.guc_log_level =	XE_DEFAULT_GUC_LOG_LEVEL,
 	.force_probe =		XE_DEFAULT_FORCE_PROBE,
@@ -38,6 +39,11 @@ module_param_named(svm_notifier_size, xe_modparam.svm_notifier_size, uint, 0600)
 MODULE_PARM_DESC(svm_notifier_size, "Set the svm notifier size in MiB, must be power of 2 "
 		 "[default=" __stringify(XE_DEFAULT_SVM_NOTIFIER_SIZE) "]");
 
+module_param_named(enable_media, xe_modparam.enable_media, bool, 0444);
+MODULE_PARM_DESC(enable_media, "Enable the media GT, when present. Disabling overrides any "
+		 "media GT selected via the gt_types_allowed configfs attribute "
+		 "[default=" __stringify(XE_DEFAULT_ENABLE_MEDIA) "])");
+
 #if IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
 module_param_named(probe_display, xe_modparam.probe_display, bool, 0444);
 MODULE_PARM_DESC(probe_display, "Probe display HW, otherwise it's left untouched "
diff --git a/drivers/gpu/drm/xe/xe_module.h b/drivers/gpu/drm/xe/xe_module.h
index 6272d9e41207..b10010e0a007 100644
--- a/drivers/gpu/drm/xe/xe_module.h
+++ b/drivers/gpu/drm/xe/xe_module.h
@@ -12,6 +12,7 @@ struct work_struct;
 
 /* Module modprobe variables */
 struct xe_modparam {
+	bool enable_media;
 	bool probe_display;
 	int force_vram_bar_size;
 	int guc_log_level;
diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index 18fa9d4f2f6d..6544c373af8c 100644
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -613,6 +613,19 @@ enum xe_gmdid_type {
 	GMDID_MEDIA
 };
 
+/*
+ * The media GT is usable only if both the enable_media modparam and the
+ * gt_types_allowed configfs attribute allow it; the modparam takes
+ * precedence and disables the media GT regardless of the configfs setting.
+ */
+static bool media_gt_allowed(struct xe_device *xe)
+{
+	if (!xe_modparam.enable_media)
+		return false;
+
+	return xe_configfs_media_gt_allowed(to_pci_dev(xe->drm.dev));
+}
+
 static int read_gmdid(struct xe_device *xe, enum xe_gmdid_type type, u32 *ver, u32 *revid)
 {
 	struct xe_mmio *mmio = xe_root_tile_mmio(xe);
@@ -634,7 +647,7 @@ static int read_gmdid(struct xe_device *xe, enum xe_gmdid_type type, u32 *ver, u
 		int err;
 
 		/* Don't try to read media ver if media GT is not allowed */
-		if (type == GMDID_MEDIA && !xe_configfs_media_gt_allowed(to_pci_dev(xe->drm.dev))) {
+		if (type == GMDID_MEDIA && !media_gt_allowed(xe)) {
 			*ver = *revid = 0;
 			return 0;
 		}
@@ -929,8 +942,8 @@ static struct xe_gt *alloc_media_gt(struct xe_tile *tile,
 	struct xe_device *xe = tile_to_xe(tile);
 	struct xe_gt *gt;
 
-	if (!xe_configfs_media_gt_allowed(to_pci_dev(xe->drm.dev))) {
-		xe_tile_info(tile, "Media GT disabled via configfs\n");
+	if (!media_gt_allowed(xe)) {
+		xe_tile_info(tile, "Media GT disabled\n");
 		return NULL;
 	}
 
-- 
2.43.0