diff options
Diffstat (limited to 'drivers/gpu/vga/vgaarb.c')
| -rw-r--r-- | drivers/gpu/vga/vgaarb.c | 110 |
1 files changed, 108 insertions, 2 deletions
diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c index f17cb0431833..1887f199ccb7 100644 --- a/drivers/gpu/vga/vgaarb.c +++ b/drivers/gpu/vga/vgaarb.c @@ -131,7 +131,24 @@ static struct vga_device *vgadev_find(struct pci_dev *pdev) return NULL; } -/* Returns the default VGA device (vgacon's babe) */ +/** + * vga_default_device - return the default VGA device, for vgacon + * + * This can be defined by the platform. The default implementation + * is rather dumb and will probably only work properly on single + * vga card setups and/or x86 platforms. + * + * If your VGA default device is not PCI, you'll have to return + * NULL here. In this case, I assume it will not conflict with + * any PCI card. If this is not true, I'll have to define two archs + * hooks for enabling/disabling the VGA default device if that is + * possible. This may be a problem with real _ISA_ VGA cards, in + * addition to a PCI one. I don't know at this point how to deal + * with that card. Can theirs IOs be disabled at all ? If not, then + * I suppose it's a matter of having the proper arch hook telling + * us about it, so we basically never allow anybody to succeed a + * vga_get()... + */ struct pci_dev *vga_default_device(void) { return vga_default; @@ -356,6 +373,40 @@ static void __vga_put(struct vga_device *vgadev, unsigned int rsrc) wake_up_all(&vga_wait_queue); } +/** + * vga_get - acquire & locks VGA resources + * @pdev: pci device of the VGA card or NULL for the system default + * @rsrc: bit mask of resources to acquire and lock + * @interruptible: blocking should be interruptible by signals ? + * + * This function acquires VGA resources for the given card and mark those + * resources locked. If the resource requested are "normal" (and not legacy) + * resources, the arbiter will first check whether the card is doing legacy + * decoding for that type of resource. If yes, the lock is "converted" into a + * legacy resource lock. + * + * The arbiter will first look for all VGA cards that might conflict and disable + * their IOs and/or Memory access, including VGA forwarding on P2P bridges if + * necessary, so that the requested resources can be used. Then, the card is + * marked as locking these resources and the IO and/or Memory accesses are + * enabled on the card (including VGA forwarding on parent P2P bridges if any). + * + * This function will block if some conflicting card is already locking one of + * the required resources (or any resource on a different bus segment, since P2P + * bridges don't differentiate VGA memory and IO afaik). You can indicate + * whether this blocking should be interruptible by a signal (for userland + * interface) or not. + * + * Must not be called at interrupt time or in atomic context. If the card + * already owns the resources, the function succeeds. Nested calls are + * supported (a per-resource counter is maintained) + * + * On success, release the VGA resource again with vga_put(). + * + * Returns: + * + * 0 on success, negative error code on failure. + */ int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible) { struct vga_device *vgadev, *conflict; @@ -408,6 +459,21 @@ int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible) } EXPORT_SYMBOL(vga_get); +/** + * vga_tryget - try to acquire & lock legacy VGA resources + * @pdev: pci devivce of VGA card or NULL for system default + * @rsrc: bit mask of resources to acquire and lock + * + * This function performs the same operation as vga_get(), but will return an + * error (-EBUSY) instead of blocking if the resources are already locked by + * another card. It can be called in any context + * + * On success, release the VGA resource again with vga_put(). + * + * Returns: + * + * 0 on success, negative error code on failure. + */ int vga_tryget(struct pci_dev *pdev, unsigned int rsrc) { struct vga_device *vgadev; @@ -435,6 +501,16 @@ bail: } EXPORT_SYMBOL(vga_tryget); +/** + * vga_put - release lock on legacy VGA resources + * @pdev: pci device of VGA card or NULL for system default + * @rsrc: but mask of resource to release + * + * This fuction releases resources previously locked by vga_get() or + * vga_tryget(). The resources aren't disabled right away, so that a subsequence + * vga_get() on the same card will succeed immediately. Resources have a + * counter, so locks are only released if the counter reaches 0. + */ void vga_put(struct pci_dev *pdev, unsigned int rsrc) { struct vga_device *vgadev; @@ -716,7 +792,37 @@ void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes) } EXPORT_SYMBOL(vga_set_legacy_decoding); -/* call with NULL to unregister */ +/** + * vga_client_register - register or unregister a VGA arbitration client + * @pdev: pci device of the VGA client + * @cookie: client cookie to be used in callbacks + * @irq_set_state: irq state change callback + * @set_vga_decode: vga decode change callback + * + * Clients have two callback mechanisms they can use. + * + * @irq_set_state callback: If a client can't disable its GPUs VGA + * resources, then we need to be able to ask it to turn off its irqs when we + * turn off its mem and io decoding. + * + * @set_vga_decode callback: If a client can disable its GPU VGA resource, it + * will get a callback from this to set the encode/decode state. + * + * Rationale: we cannot disable VGA decode resources unconditionally some single + * GPU laptops seem to require ACPI or BIOS access to the VGA registers to + * control things like backlights etc. Hopefully newer multi-GPU laptops do + * something saner, and desktops won't have any special ACPI for this. The + * driver will get a callback when VGA arbitration is first used by userspace + * since some older X servers have issues. + * + * This function does not check whether a client for @pdev has been registered + * already. + * + * To unregister just call this function with @irq_set_state and @set_vga_decode + * both set to NULL for the same @pdev as originally used to register them. + * + * Returns: 0 on success, -1 on failure + */ int vga_client_register(struct pci_dev *pdev, void *cookie, void (*irq_set_state)(void *cookie, bool state), unsigned int (*set_vga_decode)(void *cookie, |