vgaarbiter: rst-ifiy and polish kerneldoc

Move the documentation into Documentation/gpu, link it up and pull in
the kernel doc.

No actual text changes except that I did polish the kerneldoc a bit,
especially for vga_client_register().

v2: Remove some rst from vga-switcheroo.rst that I don't understand,
but which seems to be the reason why the new vgaarbiter.rst sometimes
drops out of the sidebar index.

v3: Drop one level of headings and clarify the vgaarb one a bit.

v4: Fix some typos (Sean).

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471034937-651-20-git-send-email-daniel.vetter@ffwll.ch

1 files changed, 16 insertions, 112 deletions

diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
index 8c3b412d84df..ee162e3e879b 100644
--- a/include/linux/vgaarb.h
+++ b/include/linux/vgaarb.h
@@ -73,34 +73,6 @@ static inline void vga_set_legacy_decoding(struct pci_dev *pdev,
 					   unsigned int decodes) { };
 #endif
 
-/**
- *     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 accesse 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 differenciate 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)
- */
-
 #if defined(CONFIG_VGA_ARB)
 extern int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible);
 #else
@@ -108,11 +80,14 @@ static inline int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interrupt
 #endif
 
 /**
- *     vga_get_interruptible
+ * vga_get_interruptible
+ * @pdev: pci device of the VGA card or NULL for the system default
+ * @rsrc: bit mask of resources to acquire and lock
  *
- *     Shortcut to vga_get
+ * Shortcut to vga_get with interruptible set to true.
+ *
+ * On success, release the VGA resource again with vga_put().
  */
-
 static inline int vga_get_interruptible(struct pci_dev *pdev,
 					unsigned int rsrc)
 {
@@ -120,47 +95,26 @@ static inline int vga_get_interruptible(struct pci_dev *pdev,
 }
 
 /**
- *     vga_get_uninterruptible
+ * vga_get_uninterruptible - shortcut to vga_get()
+ * @pdev: pci device of the VGA card or NULL for the system default
+ * @rsrc: bit mask of resources to acquire and lock
  *
- *     Shortcut to vga_get
+ * Shortcut to vga_get with interruptible set to false.
+ *
+ * On success, release the VGA resource again with vga_put().
  */
-
 static inline int vga_get_uninterruptible(struct pci_dev *pdev,
 					  unsigned int rsrc)
 {
        return vga_get(pdev, rsrc, 0);
 }
 
-/**
- *     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
- */
-
 #if defined(CONFIG_VGA_ARB)
 extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
 #else
 static inline int vga_tryget(struct pci_dev *pdev, unsigned int rsrc) { return 0; }
 #endif
 
-/**
- *     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 function 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.
- */
-
 #if defined(CONFIG_VGA_ARB)
 extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
 #else
@@ -168,25 +122,6 @@ extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
 #endif
 
 
-/**
- *     vga_default_device
- *
- *     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()...
- */
-
 #ifdef CONFIG_VGA_ARB
 extern struct pci_dev *vga_default_device(void);
 extern void vga_set_default_device(struct pci_dev *pdev);
@@ -195,14 +130,11 @@ static inline struct pci_dev *vga_default_device(void) { return NULL; };
 static inline void vga_set_default_device(struct pci_dev *pdev) { };
 #endif
 
-/**
- *     vga_conflicts
- *
- *     Architectures should define this if they have several
- *     independent PCI domains that can afford concurrent VGA
- *     decoding
+/*
+ * Architectures should define this if they have several
+ * independent PCI domains that can afford concurrent VGA
+ * decoding
  */
-
 #ifndef __ARCH_HAS_VGA_CONFLICT
 static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
 {
@@ -210,34 +142,6 @@ static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev *p2)
 }
 #endif
 
-/**
- *	vga_client_register
- *
- *	@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
- *
- * 	return value: 0 on success, -1 on failure
- * 	Register a client with the VGA arbitration logic
- *
- *	Clients have two callback mechanisms they can use.
- *	irq enable/disable 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
- *		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.
- * They driver will get a callback when VGA arbitration is first used
- * by userspace since we some older X servers have issues.
- */
 #if defined(CONFIG_VGA_ARB)
 int vga_client_register(struct pci_dev *pdev, void *cookie,
 			void (*irq_set_state)(void *cookie, bool state),