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-rw-r--r--drivers/gpu/vga/vgaarb.c113
-rw-r--r--drivers/pci/pci.c25
-rw-r--r--include/linux/pci.h7
3 files changed, 118 insertions, 27 deletions
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index be8d4cb5861..8a1021f2e31 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c
@@ -61,7 +61,7 @@ struct vga_device {
unsigned int mem_lock_cnt; /* legacy MEM lock count */
unsigned int io_norm_cnt; /* normal IO count */
unsigned int mem_norm_cnt; /* normal MEM count */
-
+ bool bridge_has_one_vga;
/* allow IRQ enable/disable hook */
void *cookie;
void (*irq_set_state)(void *cookie, bool enable);
@@ -165,6 +165,8 @@ static struct vga_device *__vga_tryget(struct vga_device *vgadev,
unsigned int wants, legacy_wants, match;
struct vga_device *conflict;
unsigned int pci_bits;
+ u32 flags = 0;
+
/* Account for "normal" resources to lock. If we decode the legacy,
* counterpart, we need to request it as well
*/
@@ -237,16 +239,23 @@ static struct vga_device *__vga_tryget(struct vga_device *vgadev,
/* looks like he doesn't have a lock, we can steal
* them from him
*/
- vga_irq_set_state(conflict, false);
+ flags = 0;
pci_bits = 0;
- if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
- pci_bits |= PCI_COMMAND_MEMORY;
- if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
- pci_bits |= PCI_COMMAND_IO;
- pci_set_vga_state(conflict->pdev, false, pci_bits,
- change_bridge);
+ if (!conflict->bridge_has_one_vga) {
+ vga_irq_set_state(conflict, false);
+ flags |= PCI_VGA_STATE_CHANGE_DECODES;
+ if (lwants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
+ pci_bits |= PCI_COMMAND_MEMORY;
+ if (lwants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
+ pci_bits |= PCI_COMMAND_IO;
+ }
+
+ if (change_bridge)
+ flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
+
+ pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
conflict->owns &= ~lwants;
/* If he also owned non-legacy, that is no longer the case */
if (lwants & VGA_RSRC_LEGACY_MEM)
@@ -261,14 +270,24 @@ enable_them:
* also have in "decodes". We can lock resources we don't decode but
* not own them.
*/
+ flags = 0;
pci_bits = 0;
- if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
- pci_bits |= PCI_COMMAND_MEMORY;
- if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
- pci_bits |= PCI_COMMAND_IO;
- pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants & VGA_RSRC_LEGACY_MASK));
- vga_irq_set_state(vgadev, true);
+ if (!vgadev->bridge_has_one_vga) {
+ flags |= PCI_VGA_STATE_CHANGE_DECODES;
+ if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
+ pci_bits |= PCI_COMMAND_MEMORY;
+ if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
+ pci_bits |= PCI_COMMAND_IO;
+ }
+ if (!!(wants & VGA_RSRC_LEGACY_MASK))
+ flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
+
+ pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);
+
+ if (!vgadev->bridge_has_one_vga) {
+ vga_irq_set_state(vgadev, true);
+ }
vgadev->owns |= (wants & vgadev->decodes);
lock_them:
vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
@@ -421,6 +440,62 @@ bail:
}
EXPORT_SYMBOL(vga_put);
+/* 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 for that device.
+ It should always use the bridge closest to the device to control it.
+ If a bridge has a direct VGA descendant, but also have a sub-bridge
+ VGA descendant then we cannot use that bridge to control the direct VGA descendant.
+ So for every device we register, we need to iterate all its parent bridges
+ so we can invalidate any devices using them properly.
+*/
+static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
+{
+ struct vga_device *same_bridge_vgadev;
+ struct pci_bus *new_bus, *bus;
+ struct pci_dev *new_bridge, *bridge;
+
+ vgadev->bridge_has_one_vga = true;
+
+ if (list_empty(&vga_list))
+ return;
+
+ /* okay iterate the new devices bridge hierarachy */
+ new_bus = vgadev->pdev->bus;
+ while (new_bus) {
+ new_bridge = new_bus->self;
+
+ if (new_bridge) {
+ /* go through list of devices already registered */
+ list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
+ bus = same_bridge_vgadev->pdev->bus;
+ bridge = bus->self;
+
+ /* see if the share a bridge with this device */
+ if (new_bridge == bridge) {
+ /* if their direct parent bridge is the same
+ as any bridge of this device then it can't be used
+ for that device */
+ same_bridge_vgadev->bridge_has_one_vga = false;
+ }
+
+ /* now iterate the previous devices bridge hierarchy */
+ /* if the new devices parent bridge is in the other devices
+ hierarchy then we can't use it to control this device */
+ while (bus) {
+ bridge = bus->self;
+ if (bridge) {
+ if (bridge == vgadev->pdev->bus->self)
+ vgadev->bridge_has_one_vga = false;
+ }
+ bus = bus->parent;
+ }
+ }
+ }
+ new_bus = new_bus->parent;
+ }
+}
+
/*
* Currently, we assume that the "initial" setup of the system is
* not sane, that is we come up with conflicting devices and let
@@ -500,6 +575,8 @@ static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
vga_default = pci_dev_get(pdev);
#endif
+ vga_arbiter_check_bridge_sharing(vgadev);
+
/* Add to the list */
list_add(&vgadev->list, &vga_list);
vga_count++;
@@ -1222,6 +1299,7 @@ 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)
@@ -1238,6 +1316,13 @@ static int __init vga_arb_device_init(void)
vga_arbiter_add_pci_device(pdev);
pr_info("vgaarb: loaded\n");
+
+ list_for_each_entry(vgadev, &vga_list, list) {
+ if (vgadev->bridge_has_one_vga)
+ pr_info("vgaarb: bridge control possible %s\n", pci_name(vgadev->pdev));
+ else
+ pr_info("vgaarb: no bridge control possible %s\n", pci_name(vgadev->pdev));
+ }
return rc;
}
subsys_initcall(vga_arb_device_init);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 2472e7177b4..a339237f4f9 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2875,31 +2875,34 @@ static int pci_set_vga_state_arch(struct pci_dev *dev, bool decode,
* @dev: the PCI device
* @decode: true = enable decoding, false = disable decoding
* @command_bits: PCI_COMMAND_IO and/or PCI_COMMAND_MEMORY
- * @change_bridge: traverse ancestors and change bridges
+ * @change_bridge_flags: traverse ancestors and change bridges
+ * CHANGE_BRIDGE_ONLY / CHANGE_BRIDGE
*/
int pci_set_vga_state(struct pci_dev *dev, bool decode,
- unsigned int command_bits, bool change_bridge)
+ unsigned int command_bits, u32 flags)
{
struct pci_bus *bus;
struct pci_dev *bridge;
u16 cmd;
int rc;
- WARN_ON(command_bits & ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY));
+ WARN_ON((flags & PCI_VGA_STATE_CHANGE_DECODES) & (command_bits & ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY)));
/* ARCH specific VGA enables */
- rc = pci_set_vga_state_arch(dev, decode, command_bits, change_bridge);
+ rc = pci_set_vga_state_arch(dev, decode, command_bits, flags);
if (rc)
return rc;
- pci_read_config_word(dev, PCI_COMMAND, &cmd);
- if (decode == true)
- cmd |= command_bits;
- else
- cmd &= ~command_bits;
- pci_write_config_word(dev, PCI_COMMAND, cmd);
+ if (flags & PCI_VGA_STATE_CHANGE_DECODES) {
+ pci_read_config_word(dev, PCI_COMMAND, &cmd);
+ if (decode == true)
+ cmd |= command_bits;
+ else
+ cmd &= ~command_bits;
+ pci_write_config_word(dev, PCI_COMMAND, cmd);
+ }
- if (change_bridge == false)
+ if (!(flags & PCI_VGA_STATE_CHANGE_BRIDGE))
return 0;
bus = dev->bus;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 96f70d7e058..f2e57b2e6a8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -915,8 +915,11 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
int pci_cfg_space_size(struct pci_dev *dev);
unsigned char pci_bus_max_busnr(struct pci_bus *bus);
+#define PCI_VGA_STATE_CHANGE_BRIDGE (1 << 0)
+#define PCI_VGA_STATE_CHANGE_DECODES (1 << 1)
+
int pci_set_vga_state(struct pci_dev *pdev, bool decode,
- unsigned int command_bits, bool change_bridge);
+ unsigned int command_bits, u32 flags);
/* kmem_cache style wrapper around pci_alloc_consistent() */
#include <linux/pci-dma.h>
@@ -1061,7 +1064,7 @@ static inline int pci_proc_domain(struct pci_bus *bus)
/* some architectures require additional setup to direct VGA traffic */
typedef int (*arch_set_vga_state_t)(struct pci_dev *pdev, bool decode,
- unsigned int command_bits, bool change_bridge);
+ unsigned int command_bits, u32 flags);
extern void pci_register_set_vga_state(arch_set_vga_state_t func);
#else /* CONFIG_PCI is not enabled */
generated by cgit v1.2.3-70-g09d2 (git 2.51.2) at 2025-11-04 09:03:15 +0000