From ed1d33f16fdee0ab9b4e21cd8b93fcf6008cb0c6 Mon Sep 17 00:00:00 2001
From: xiota <>
Date: Thu, 30 Apr 2026 00:46:34 +0000
Subject: [PATCH] i915-vga-arbiter

---
 .../drm/i915/display/intel_display_driver.c   | 24 ++++++++++--
 .../drm/i915/display/intel_display_driver.h   |  4 ++
 .../drm/i915/display/intel_display_params.c   |  3 ++
 .../drm/i915/display/intel_display_params.h   |  1 +
 drivers/gpu/drm/i915/display/intel_vga.c      | 39 +++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_vga.h      |  6 +++
 drivers/gpu/drm/xe/Makefile                   |  1 +
 i                                             |  0
 8 files changed, 75 insertions(+), 3 deletions(-)
 create mode 100644 i

diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.c b/drivers/gpu/drm/i915/display/intel_display_driver.c
index 268b1de45..98e1de0ff 100644
--- a/drivers/gpu/drm/i915/display/intel_display_driver.c
+++ b/drivers/gpu/drm/i915/display/intel_display_driver.c
@@ -33,6 +33,7 @@
 #include "intel_display_debugfs.h"
 #include "intel_display_driver.h"
 #include "intel_display_irq.h"
+#include "intel_display_params.h"
 #include "intel_display_power.h"
 #include "intel_display_types.h"
 #include "intel_display_utils.h"
@@ -208,9 +209,11 @@ int intel_display_driver_probe_noirq(struct intel_display *display)
 
 	intel_bios_init(display);
 
-	ret = intel_vga_register(display);
-	if (ret)
-		goto cleanup_bios;
+	if (!display->params.enable_hd_vgaarb || !HAS_PCH_SPLIT(display)) {
+		ret = intel_vga_register(display);
+		if (ret)
+			goto cleanup_bios;
+	}
 
 	intel_psr_dc5_dc6_wa_init(display);
 
@@ -538,6 +541,14 @@ int intel_display_driver_probe(struct intel_display *display)
 
 	intel_overlay_setup(display);
 
+#ifndef VGA_ARBITER_BUILD_XE
+	/*
+	 * Must do this after fbcon init so that
+	 * vgacon_save_screen() works during the handover.
+	 */
+	intel_vga_disable_mem(display);
+#endif /* VGA_ARBITER_BUILD_XE */
+
 	/* Only enable hotplug handling once the fbdev is fully set up. */
 	intel_hpd_init(display);
 
@@ -588,6 +599,10 @@ void intel_display_driver_remove(struct intel_display *display)
 	if (!HAS_DISPLAY(display))
 		return;
 
+#ifndef VGA_ARBITER_BUILD_XE
+	intel_vga_enable_mem(display);
+#endif /* VGA_ARBITER_BUILD_XE */
+
 	flush_workqueue(display->wq.flip);
 	flush_workqueue(display->wq.modeset);
 	flush_workqueue(display->wq.cleanup);
@@ -618,6 +633,9 @@ void intel_display_driver_remove_noirq(struct intel_display *display)
 	intel_unregister_dsm_handler();
 
 	/* flush any delayed tasks or pending work */
+#ifndef VGA_ARBITER_BUILD_XE
+	intel_vga_enable_mem(display);
+#endif /* VGA_ARBITER_BUILD_XE */
 	flush_workqueue(display->wq.unordered);
 
 	intel_hdcp_component_fini(display);
diff --git a/drivers/gpu/drm/i915/display/intel_display_driver.h b/drivers/gpu/drm/i915/display/intel_display_driver.h
index 2966ff91b..939124c3b 100644
--- a/drivers/gpu/drm/i915/display/intel_display_driver.h
+++ b/drivers/gpu/drm/i915/display/intel_display_driver.h
@@ -13,6 +13,10 @@ struct drm_modeset_acquire_ctx;
 struct intel_display;
 struct pci_dev;
 
+#ifndef VGA_ARBITER_BUILD_XE
+extern void intel_vga_disable_mem(struct intel_display *display);
+#endif /* VGA_ARBITER_BUILD_XE */
+
 bool intel_display_driver_probe_defer(struct pci_dev *pdev);
 void intel_display_driver_init_hw(struct intel_display *display);
 void intel_display_driver_early_probe(struct intel_display *display);
diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c b/drivers/gpu/drm/i915/display/intel_display_params.c
index 2aed110c5..db4fbf207 100644
--- a/drivers/gpu/drm/i915/display/intel_display_params.c
+++ b/drivers/gpu/drm/i915/display/intel_display_params.c
@@ -102,6 +102,9 @@ intel_display_param_named_unsafe(force_reset_modeset_test, bool, 0400,
 intel_display_param_named(disable_display, bool, 0400,
 	"Disable display (default: false)");
 
+intel_display_param_named(enable_hd_vgaarb, bool, 0400,
+	"Enable support for VGA arbitration on Intel HD IGD. (default: false)");
+
 intel_display_param_named(verbose_state_checks, bool, 0400,
 	"Enable verbose logs (ie. WARN_ON()) in case of unexpected hw state conditions.");
 
diff --git a/drivers/gpu/drm/i915/display/intel_display_params.h b/drivers/gpu/drm/i915/display/intel_display_params.h
index b95ecf728..6e01bf1b0 100644
--- a/drivers/gpu/drm/i915/display/intel_display_params.h
+++ b/drivers/gpu/drm/i915/display/intel_display_params.h
@@ -41,6 +41,7 @@ struct drm_printer;
 	param(bool, load_detect_test, false, 0600) \
 	param(bool, force_reset_modeset_test, false, 0600) \
 	param(bool, disable_display, false, 0400) \
+	param(bool, enable_hd_vgaarb, false, 0400) \
 	param(bool, verbose_state_checks, true, 0400) \
 	param(bool, nuclear_pageflip, false, 0400) \
 	param(bool, enable_dp_mst, true, 0600) \
diff --git a/drivers/gpu/drm/i915/display/intel_vga.c b/drivers/gpu/drm/i915/display/intel_vga.c
index c45c4bbc3..1fef50f2e 100644
--- a/drivers/gpu/drm/i915/display/intel_vga.c
+++ b/drivers/gpu/drm/i915/display/intel_vga.c
@@ -12,8 +12,16 @@
 #include <drm/intel/i915_drm.h>
 #include <video/vga.h>
 
+#ifndef VGA_ARBITER_BUILD_XE
+#warning "Building i915 version — i915 header included"
+#include "i915_drv.h"
+#else /* VGA_ARBITER_BUILD_XE */
+#warning "Building XE version — i915 header excluded"
+#endif /* VGA_ARBITER_BUILD_XE */
+
 #include "intel_de.h"
 #include "intel_display.h"
+#include "intel_display_params.h"
 #include "intel_display_types.h"
 #include "intel_vga.h"
 #include "intel_vga_regs.h"
@@ -76,6 +84,37 @@ void intel_vga_disable(struct intel_display *display)
 	intel_de_posting_read(display, vga_reg);
 }
 
+#ifndef VGA_ARBITER_BUILD_XE
+void intel_vga_enable_mem(struct intel_display *display)
+{
+	struct pci_dev *pdev = to_pci_dev(display->drm->dev);
+	/* Enable VGA memory on Intel HD */
+	if (display->params.enable_hd_vgaarb && HAS_PCH_SPLIT(display)) {
+		vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
+		outb(inb(VGA_MIS_R) | (1 << 1), VGA_MIS_W);
+		vga_set_legacy_decoding(pdev, VGA_RSRC_LEGACY_IO |
+						VGA_RSRC_LEGACY_MEM |
+						VGA_RSRC_NORMAL_IO |
+						VGA_RSRC_NORMAL_MEM);
+		vga_put(pdev, VGA_RSRC_LEGACY_IO);
+	}
+}
+
+void intel_vga_disable_mem(struct intel_display *display)
+{
+	struct pci_dev *pdev = to_pci_dev(display->drm->dev);
+	/* Disable VGA memory on Intel HD */
+	if (display->params.enable_hd_vgaarb && HAS_PCH_SPLIT(display)) {
+		vga_get_uninterruptible(pdev, VGA_RSRC_LEGACY_IO);
+		outb(inb(VGA_MIS_R) & ~(1 << 1), VGA_MIS_W);
+		vga_set_legacy_decoding(pdev, VGA_RSRC_LEGACY_IO |
+						   VGA_RSRC_NORMAL_IO |
+						   VGA_RSRC_NORMAL_MEM);
+		vga_put(pdev, VGA_RSRC_LEGACY_IO);
+	}
+}
+#endif /* VGA_ARBITER_BUILD_XE */
+
 void intel_vga_reset_io_mem(struct intel_display *display)
 {
 	struct pci_dev *pdev = to_pci_dev(display->drm->dev);
diff --git a/drivers/gpu/drm/i915/display/intel_vga.h b/drivers/gpu/drm/i915/display/intel_vga.h
index 16d699f3b..a20721eb6 100644
--- a/drivers/gpu/drm/i915/display/intel_vga.h
+++ b/drivers/gpu/drm/i915/display/intel_vga.h
@@ -13,4 +13,10 @@ void intel_vga_disable(struct intel_display *display);
 int intel_vga_register(struct intel_display *display);
 void intel_vga_unregister(struct intel_display *display);
 
+#ifndef VGA_ARBITER_BUILD_XE
+/* i915 vga arb patch */
+void intel_vga_enable_mem(struct intel_display *display);
+void intel_vga_disable_mem(struct intel_display *display);
+#endif /* VGA_ARBITER_BUILD_XE */
+
 #endif /* __INTEL_VGA_H__ */
diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index b39cbb756..4506996e1 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -199,6 +199,7 @@ endif
 
 # i915 Display compat #defines and #includes
 subdir-ccflags-$(CONFIG_DRM_XE_DISPLAY) += \
+	-DVGA_ARBITER_BUILD_XE=1 \
 	-I$(src)/compat-i915-headers \
 	-I$(srctree)/drivers/gpu/drm/i915/display/
 
diff --git a/i b/i
new file mode 100644
index 000000000..e69de29bb
-- 
2.54.0