Merge branch 'pci/vga'

- Move vgaarb.c from drivers/gpu/vga to drivers/pci (Bjorn Helgaas)

- Factor out default VGA device selection (Huacai Chen)

- Move firmware default device detection to ADD_DEVICE path so we can
  select a default device regardless of whether it is enumerated before or
  after vga_arb_device_init() (Huacai Chen)

- Move non-legacy VGA detection to ADD_DEVICE path (Huacai Chen)

- Move disabled VGA device detection to ADD_DEVICE path (Huacai Chen)

* pci/vga:
  PCI/VGA: Replace full MIT license text with SPDX identifier
  PCI/VGA: Use unsigned format string to print lock counts
  PCI/VGA: Log bridge control messages when adding devices
  PCI/VGA: Remove empty vga_arb_device_card_gone()
  PCI/VGA: Move disabled VGA device detection to ADD_DEVICE path
  PCI/VGA: Move non-legacy VGA detection to ADD_DEVICE path
  PCI/VGA: Move firmware default device detection to ADD_DEVICE path
  PCI/VGA: Factor out default VGA device selection
  PCI/VGA: Factor out vga_select_framebuffer_device()
  PCI/VGA: Move vga_arb_integrated_gpu() earlier in file
  PCI/VGA: Move vgaarb to drivers/pci

Documentation/gpu/vgaarbiter.rst

@@ -100,7 +100,7 @@ In-kernel interface
 .. kernel-doc:: include/linux/vgaarb.h
    :internal:
 
-.. kernel-doc:: drivers/gpu/vga/vgaarb.c
+.. kernel-doc:: drivers/pci/vgaarb.c
    :export:
 
 libpciaccess

drivers/gpu/vga/Kconfig

@@ -1,23 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-config VGA_ARB
-	bool "VGA Arbitration" if EXPERT
-	default y
-	depends on (PCI && !S390)
-	help
-	  Some "legacy" VGA devices implemented on PCI typically have the same
-	  hard-decoded addresses as they did on ISA. When multiple PCI devices
-	  are accessed at same time they need some kind of coordination. Please
-	  see Documentation/gpu/vgaarbiter.rst for more details. Select this to
-	  enable VGA arbiter.
-
-config VGA_ARB_MAX_GPUS
-	int "Maximum number of GPUs"
-	default 16
-	depends on VGA_ARB
-	help
-	  Reserves space in the kernel to maintain resource locking for
-	  multiple GPUS.  The overhead for each GPU is very small.
-
 config VGA_SWITCHEROO
 	bool "Laptop Hybrid Graphics - GPU switching support"
 	depends on X86

drivers/gpu/vga/Makefile

@@ -1,3 +1,2 @@
 # SPDX-License-Identifier: GPL-2.0-only
-obj-$(CONFIG_VGA_ARB)  += vgaarb.o
 obj-$(CONFIG_VGA_SWITCHEROO) += vga_switcheroo.o

drivers/pci/Kconfig

@@ -252,6 +252,25 @@ config PCIE_BUS_PEER2PEER
 
 endchoice
 
+config VGA_ARB
+	bool "VGA Arbitration" if EXPERT
+	default y
+	depends on (PCI && !S390)
+	help
+	  Some "legacy" VGA devices implemented on PCI typically have the same
+	  hard-decoded addresses as they did on ISA. When multiple PCI devices
+	  are accessed at same time they need some kind of coordination. Please
+	  see Documentation/gpu/vgaarbiter.rst for more details. Select this to
+	  enable VGA arbiter.
+
+config VGA_ARB_MAX_GPUS
+	int "Maximum number of GPUs"
+	default 16
+	depends on VGA_ARB
+	help
+	  Reserves space in the kernel to maintain resource locking for
+	  multiple GPUS.  The overhead for each GPU is very small.
+
 source "drivers/pci/hotplug/Kconfig"
 source "drivers/pci/controller/Kconfig"
 source "drivers/pci/endpoint/Kconfig"

drivers/pci/Makefile

@@ -30,6 +30,7 @@ obj-$(CONFIG_PCI_PF_STUB)	+= pci-pf-stub.o
 obj-$(CONFIG_PCI_ECAM)		+= ecam.o
 obj-$(CONFIG_PCI_P2PDMA)	+= p2pdma.o
 obj-$(CONFIG_XEN_PCIDEV_FRONTEND) += xen-pcifront.o
+obj-$(CONFIG_VGA_ARB)		+= vgaarb.o
 
 # Endpoint library must be initialized before its users
 obj-$(CONFIG_PCI_ENDPOINT)	+= endpoint/

drivers/pci/vgaarb.c

@@ -1,32 +1,11 @@
+// SPDX-License-Identifier: MIT
 /*
  * vgaarb.c: Implements the VGA arbitration. For details refer to
  * Documentation/gpu/vgaarbiter.rst
  *
- *
  * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
  * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
  * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice (including the next
- * paragraph) shall be included in all copies or substantial portions of the
- * Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
- * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS
- * IN THE SOFTWARE.
- *
  */
 
 #define pr_fmt(fmt) "vgaarb: " fmt
@@ -72,6 +51,7 @@ struct vga_device {
 	unsigned int io_norm_cnt;	/* normal IO count */
 	unsigned int mem_norm_cnt;	/* normal MEM count */
 	bool bridge_has_one_vga;
+	bool is_firmware_default;	/* device selected by firmware */
 	unsigned int (*set_decode)(struct pci_dev *pdev, bool decode);
 };
 
@@ -122,8 +102,6 @@ both:
 /* this is only used a cookie - it should not be dereferenced */
 static struct pci_dev *vga_default;
 
-static void vga_arb_device_card_gone(struct pci_dev *pdev);
-
 /* Find somebody in our list */
 static struct vga_device *vgadev_find(struct pci_dev *pdev)
 {
@@ -565,6 +543,144 @@ bail:
 }
 EXPORT_SYMBOL(vga_put);
 
+static bool vga_is_firmware_default(struct pci_dev *pdev)
+{
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
+	u64 base = screen_info.lfb_base;
+	u64 size = screen_info.lfb_size;
+	u64 limit;
+	resource_size_t start, end;
+	unsigned long flags;
+	int i;
+
+	/* Select the device owning the boot framebuffer if there is one */
+
+	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
+		base |= (u64)screen_info.ext_lfb_base << 32;
+
+	limit = base + size;
+
+	/* Does firmware framebuffer belong to us? */
+	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
+		flags = pci_resource_flags(pdev, i);
+
+		if ((flags & IORESOURCE_MEM) == 0)
+			continue;
+
+		start = pci_resource_start(pdev, i);
+		end  = pci_resource_end(pdev, i);
+
+		if (!start || !end)
+			continue;
+
+		if (base < start || limit >= end)
+			continue;
+
+		return true;
+	}
+#endif
+	return false;
+}
+
+static bool vga_arb_integrated_gpu(struct device *dev)
+{
+#if defined(CONFIG_ACPI)
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+
+	return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);
+#else
+	return false;
+#endif
+}
+
+/*
+ * Return true if vgadev is a better default VGA device than the best one
+ * we've seen so far.
+ */
+static bool vga_is_boot_device(struct vga_device *vgadev)
+{
+	struct vga_device *boot_vga = vgadev_find(vga_default_device());
+	struct pci_dev *pdev = vgadev->pdev;
+	u16 cmd, boot_cmd;
+
+	/*
+	 * We select the default VGA device in this order:
+	 *   Firmware framebuffer (see vga_arb_select_default_device())
+	 *   Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)
+	 *   Non-legacy integrated device (see vga_arb_select_default_device())
+	 *   Non-legacy discrete device (see vga_arb_select_default_device())
+	 *   Other device (see vga_arb_select_default_device())
+	 */
+
+	/*
+	 * We always prefer a firmware default device, so if we've already
+	 * found one, there's no need to consider vgadev.
+	 */
+	if (boot_vga && boot_vga->is_firmware_default)
+		return false;
+
+	if (vga_is_firmware_default(pdev)) {
+		vgadev->is_firmware_default = true;
+		return true;
+	}
+
+	/*
+	 * A legacy VGA device has MEM and IO enabled and any bridges
+	 * leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy
+	 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are
+	 * routed to it.
+	 *
+	 * We use the first one we find, so if we've already found one,
+	 * vgadev is no better.
+	 */
+	if (boot_vga &&
+	    (boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
+		return false;
+
+	if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
+		return true;
+
+	/*
+	 * If we haven't found a legacy VGA device, accept a non-legacy
+	 * device.  It may have either IO or MEM enabled, and bridges may
+	 * not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to
+	 * use legacy VGA resources.  Prefer an integrated GPU over others.
+	 */
+	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
+	if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
+
+		/*
+		 * An integrated GPU overrides a previous non-legacy
+		 * device.  We expect only a single integrated GPU, but if
+		 * there are more, we use the *last* because that was the
+		 * previous behavior.
+		 */
+		if (vga_arb_integrated_gpu(&pdev->dev))
+			return true;
+
+		/*
+		 * We prefer the first non-legacy discrete device we find.
+		 * If we already found one, vgadev is no better.
+		 */
+		if (boot_vga) {
+			pci_read_config_word(boot_vga->pdev, PCI_COMMAND,
+					     &boot_cmd);
+			if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
+				return false;
+		}
+		return true;
+	}
+
+	/*
+	 * vgadev has neither IO nor MEM enabled.  If we haven't found any
+	 * other VGA devices, it is the best candidate so far.
+	 */
+	if (!boot_vga)
+		return true;
+
+	return false;
+}
+
 /*
  * Rules for using a bridge to control a VGA descendant decoding: if a bridge
  * has only one VGA descendant then it can be used to control the VGA routing
@@ -582,8 +698,10 @@ static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
 
 	vgadev->bridge_has_one_vga = true;
 
-	if (list_empty(&vga_list))
+	if (list_empty(&vga_list)) {
+		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
 		return;
+	}
 
 	/* okay iterate the new devices bridge hierarachy */
 	new_bus = vgadev->pdev->bus;
@@ -622,6 +740,11 @@ static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
 		}
 		new_bus = new_bus->parent;
 	}
+
+	if (vgadev->bridge_has_one_vga)
+		vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
+	else
+		vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
 }
 
 /*
@@ -692,12 +815,10 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
 		bus = bus->parent;
 	}
 
-	/* Deal with VGA default device. Use first enabled one
-	 * by default if arch doesn't have it's own hook
-	 */
-	if (vga_default == NULL &&
-	    ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)) {
-		vgaarb_info(&pdev->dev, "setting as boot VGA device\n");
+	if (vga_is_boot_device(vgadev)) {
+		vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
+			    vga_default_device() ?
+			    " (overriding previous)" : "");
 		vga_set_default_device(pdev);
 	}
 
@@ -741,10 +862,6 @@ static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
 	/* Remove entry from list */
 	list_del(&vgadev->list);
 	vga_count--;
-	/* Notify userland driver that the device is gone so it discards
-	 * it's copies of the pci_dev pointer
-	 */
-	vga_arb_device_card_gone(pdev);
 
 	/* Wake up all possible waiters */
 	wake_up_all(&vga_wait_queue);
@@ -994,9 +1111,7 @@ static ssize_t vga_arb_read(struct file *file, char __user *buf,
 	if (lbuf == NULL)
 		return -ENOMEM;
 
-	/* Shields against vga_arb_device_card_gone (pci_dev going
-	 * away), and allows access to vga list
-	 */
+	/* Protects vga_list */
 	spin_lock_irqsave(&vga_lock, flags);
 
 	/* If we are targeting the default, use it */
@@ -1013,8 +1128,6 @@ static ssize_t vga_arb_read(struct file *file, char __user *buf,
 		/* Wow, it's not in the list, that shouldn't happen,
 		 * let's fix us up and return invalid card
 		 */
-		if (pdev == priv->target)
-			vga_arb_device_card_gone(pdev);
 		spin_unlock_irqrestore(&vga_lock, flags);
 		len = sprintf(lbuf, "invalid");
 		goto done;
@@ -1022,7 +1135,7 @@ static ssize_t vga_arb_read(struct file *file, char __user *buf,
 
 	/* Fill the buffer with infos */
 	len = snprintf(lbuf, 1024,
-		       "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
+		       "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%u:%u)\n",
 		       vga_decode_count, pci_name(pdev),
 		       vga_iostate_to_str(vgadev->decodes),
 		       vga_iostate_to_str(vgadev->owns),
@@ -1358,10 +1471,6 @@ static int vga_arb_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static void vga_arb_device_card_gone(struct pci_dev *pdev)
-{
-}
-
 /*
  * callback any registered clients to let them know we have a
  * change in VGA cards
@@ -1430,111 +1539,10 @@ static struct miscdevice vga_arb_device = {
 	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
 };
 
-#if defined(CONFIG_ACPI)
-static bool vga_arb_integrated_gpu(struct device *dev)
-{
-	struct acpi_device *adev = ACPI_COMPANION(dev);
-
-	return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);
-}
-#else
-static bool vga_arb_integrated_gpu(struct device *dev)
-{
-	return false;
-}
-#endif
-
-static void __init vga_arb_select_default_device(void)
-{
-	struct pci_dev *pdev, *found = NULL;
-	struct vga_device *vgadev;
-
-#if defined(CONFIG_X86) || defined(CONFIG_IA64)
-	u64 base = screen_info.lfb_base;
-	u64 size = screen_info.lfb_size;
-	u64 limit;
-	resource_size_t start, end;
-	unsigned long flags;
-	int i;
-
-	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
-		base |= (u64)screen_info.ext_lfb_base << 32;
-
-	limit = base + size;
-
-	list_for_each_entry(vgadev, &vga_list, list) {
-		struct device *dev = &vgadev->pdev->dev;
-		/*
-		 * Override vga_arbiter_add_pci_device()'s I/O based detection
-		 * as it may take the wrong device (e.g. on Apple system under
-		 * EFI).
-		 *
-		 * Select the device owning the boot framebuffer if there is
-		 * one.
-		 */
-
-		/* Does firmware framebuffer belong to us? */
-		for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
-			flags = pci_resource_flags(vgadev->pdev, i);
-
-			if ((flags & IORESOURCE_MEM) == 0)
-				continue;
-
-			start = pci_resource_start(vgadev->pdev, i);
-			end  = pci_resource_end(vgadev->pdev, i);
-
-			if (!start || !end)
-				continue;
-
-			if (base < start || limit >= end)
-				continue;
-
-			if (!vga_default_device())
-				vgaarb_info(dev, "setting as boot device\n");
-			else if (vgadev->pdev != vga_default_device())
-				vgaarb_info(dev, "overriding boot device\n");
-			vga_set_default_device(vgadev->pdev);
-		}
-	}
-#endif
-
-	if (!vga_default_device()) {
-		list_for_each_entry_reverse(vgadev, &vga_list, list) {
-			struct device *dev = &vgadev->pdev->dev;
-			u16 cmd;
-
-			pdev = vgadev->pdev;
-			pci_read_config_word(pdev, PCI_COMMAND, &cmd);
-			if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
-				found = pdev;
-				if (vga_arb_integrated_gpu(dev))
-					break;
-			}
-		}
-	}
-
-	if (found) {
-		vgaarb_info(&found->dev, "setting as boot device (VGA legacy resources not available)\n");
-		vga_set_default_device(found);
-		return;
-	}
-
-	if (!vga_default_device()) {
-		vgadev = list_first_entry_or_null(&vga_list,
-						  struct vga_device, list);
-		if (vgadev) {
-			struct device *dev = &vgadev->pdev->dev;
-			vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");
-			vga_set_default_device(vgadev->pdev);
-		}
-	}
-}
-
 static int __init vga_arb_device_init(void)
 {
 	int rc;
 	struct pci_dev *pdev;
-	struct vga_device *vgadev;
 
 	rc = misc_register(&vga_arb_device);
 	if (rc < 0)
@@ -1550,18 +1558,7 @@ static int __init vga_arb_device_init(void)
 			       PCI_ANY_ID, pdev)) != NULL)
 		vga_arbiter_add_pci_device(pdev);
 
-	list_for_each_entry(vgadev, &vga_list, list) {
-		struct device *dev = &vgadev->pdev->dev;
-
-		if (vgadev->bridge_has_one_vga)
-			vgaarb_info(dev, "bridge control possible\n");
-		else
-			vgaarb_info(dev, "no bridge control possible\n");
-	}
-
-	vga_arb_select_default_device();
-
 	pr_info("loaded\n");
 	return rc;
 }
-subsys_initcall(vga_arb_device_init);
+subsys_initcall_sync(vga_arb_device_init);