Skip to content

L
linux
Commit 2c269b09 authored by Daniel Vetter's avatar Daniel Vetter
Browse files
Options

dma-fence: Some kerneldoc polish for dma-fence.h 

- Switch to inline member docs for dma_fence_ops.
- Mild polish all around.
- hyperlink all the things!

v2: - Remove the various [in] annotations, they seem really uncommon
in kerneldoc and look funny.

v3: Linebreak the "Returns" part of the @fill_driver_data kerneldoc
(Eric).
Signed-off-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Reviewed-by: default avatarEric Anholt <eric@anholt.net>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180427061724.28497-2-daniel.vetter@ffwll.ch
parent 58badaa7
Show whitespace changes
Inline Side-by-side
Showing with 155 additions and 81 deletions
include/linux/dma-fence.h
View file @ 2c269b09
......@@ -94,11 +94,11 @@ typedef void (*dma_fence_func_t)(struct dma_fence *fence,
struct dma_fence_cb *cb);
/**
* struct dma_fence_cb - callback for dma_fence_add_callback
* @node: used by dma_fence_add_callback to append this struct to fence::cb_list
* struct dma_fence_cb - callback for dma_fence_add_callback()
* @node: used by dma_fence_add_callback() to append this struct to fence::cb_list
* @func: dma_fence_func_t to call
*
* This struct will be initialized by dma_fence_add_callback, additional
* This struct will be initialized by dma_fence_add_callback(), additional
* data can be passed along by embedding dma_fence_cb in another struct.
*/
struct dma_fence_cb {
......@@ -108,25 +108,45 @@ struct dma_fence_cb {
/**
* struct dma_fence_ops - operations implemented for fence
* @get_driver_name: returns the driver name.
* @get_timeline_name: return the name of the context this fence belongs to.
* @enable_signaling: enable software signaling of fence.
* @signaled: [optional] peek whether the fence is signaled, can be null.
* @wait: custom wait implementation, or dma_fence_default_wait.
* @release: [optional] called on destruction of fence, can be null
* @fill_driver_data: [optional] callback to fill in free-form debug info
* Returns amount of bytes filled, or -errno.
* @fence_value_str: [optional] fills in the value of the fence as a string
* @timeline_value_str: [optional] fills in the current value of the timeline
* as a string
*
* Notes on enable_signaling:
*
*/
struct dma_fence_ops {
/**
* @get_driver_name:
*
* Returns the driver name. This is a callback to allow drivers to
* compute the name at runtime, without having it to store permanently
* for each fence, or build a cache of some sort.
*
* This callback is mandatory.
*/
const char * (*get_driver_name)(struct dma_fence *fence);
/**
* @get_timeline_name:
*
* Return the name of the context this fence belongs to. This is a
* callback to allow drivers to compute the name at runtime, without
* having it to store permanently for each fence, or build a cache of
* some sort.
*
* This callback is mandatory.
*/
const char * (*get_timeline_name)(struct dma_fence *fence);
/**
* @enable_signaling:
*
* Enable software signaling of fence.
*
* For fence implementations that have the capability for hw->hw
* signaling, they can implement this op to enable the necessary
* irqs, or insert commands into cmdstream, etc. This is called
* in the first wait() or add_callback() path to let the fence
* implementation know that there is another driver waiting on
* the signal (ie. hw->sw case).
* interrupts, or insert commands into cmdstream, etc, to avoid these
* costly operations for the common case where only hw->hw
* synchronization is required. This is called in the first
* dma_fence_wait() or dma_fence_add_callback() path to let the fence
* implementation know that there is another driver waiting on the
* signal (ie. hw->sw case).
*
* This function can be called from atomic context, but not
* from irq context, so normal spinlocks can be used.
......@@ -135,21 +155,43 @@ struct dma_fence_cb {
* or some failure occurred that made it impossible to enable
* signaling. True indicates successful enabling.
*
* fence->error may be set in enable_signaling, but only when false is
* returned.
* &dma_fence.error may be set in enable_signaling, but only when false
* is returned.
*
* Since many implementations can call dma_fence_signal() even when before
* @enable_signaling has been called there's a race window, where the
* dma_fence_signal() might result in the final fence reference being
* released and its memory freed. To avoid this, implementations of this
* callback should grab their own reference using dma_fence_get(), to be
* released when the fence is signalled (through e.g. the interrupt
* handler).
*
* This callback is mandatory.
*/
bool (*enable_signaling)(struct dma_fence *fence);
/**
* @signaled:
*
* Peek whether the fence is signaled, as a fastpath optimization for
* e.g. dma_fence_wait() or dma_fence_add_callback(). Note that this
* callback does not need to make any guarantees beyond that a fence
* once indicates as signalled must always return true from this
* callback. This callback may return false even if the fence has
* completed already, in this case information hasn't propogated throug
* the system yet. See also dma_fence_is_signaled().
*
* Calling dma_fence_signal before enable_signaling is called allows
* for a tiny race window in which enable_signaling is called during,
* before, or after dma_fence_signal. To fight this, it is recommended
* that before enable_signaling returns true an extra reference is
* taken on the fence, to be released when the fence is signaled.
* This will mean dma_fence_signal will still be called twice, but
* the second time will be a noop since it was already signaled.
* May set &dma_fence.error if returning true.
*
* This callback is optional.
*/
bool (*signaled)(struct dma_fence *fence);
/**
* @wait:
*
* Notes on signaled:
* May set fence->error if returning true.
* Custom wait implementation, or dma_fence_default_wait.
*
* Notes on wait:
* Must not be NULL, set to dma_fence_default_wait for default implementation.
* the dma_fence_default_wait implementation should work for any fence, as long
* as enable_signaling works correctly.
......@@ -160,23 +202,49 @@ struct dma_fence_cb {
* which should be treated as if the fence is signaled. For example a hardware
* lockup could be reported like that.
*
* Notes on release:
* Can be NULL, this function allows additional commands to run on
* destruction of the fence. Can be called from irq context.
* If pointer is set to NULL, kfree will get called instead.
* This callback is mandatory.
*/
struct dma_fence_ops {
const char * (*get_driver_name)(struct dma_fence *fence);
const char * (*get_timeline_name)(struct dma_fence *fence);
bool (*enable_signaling)(struct dma_fence *fence);
bool (*signaled)(struct dma_fence *fence);
signed long (*wait)(struct dma_fence *fence,
bool intr, signed long timeout);
/**
* @release:
*
* Called on destruction of fence to release additional resources.
* Can be called from irq context. This callback is optional. If it is
* NULL, then dma_fence_free() is instead called as the default
* implementation.
*/
void (*release)(struct dma_fence *fence);
/**
* @fill_driver_data:
*
* Callback to fill in free-form debug info.
*
* Returns amount of bytes filled, or negative error on failure.
*
* This callback is optional.
*/
int (*fill_driver_data)(struct dma_fence *fence, void *data, int size);
/**
* @fence_value_str:
*
* Callback to fill in free-form debug info specific to this fence, like
* the sequence number.
*
* This callback is optional.
*/
void (*fence_value_str)(struct dma_fence *fence, char *str, int size);
/**
* @timeline_value_str:
*
* Fills in the current value of the timeline as a string, like the
* sequence number. This should match what @fill_driver_data prints for
* the most recently signalled fence (assuming no delayed signalling).
*/
void (*timeline_value_str)(struct dma_fence *fence,
char *str, int size);
};
......@@ -189,7 +257,7 @@ void dma_fence_free(struct dma_fence *fence);
/**
* dma_fence_put - decreases refcount of the fence
* @fence: [in] fence to reduce refcount of
* @fence: fence to reduce refcount of
*/
static inline void dma_fence_put(struct dma_fence *fence)
{
......@@ -199,7 +267,7 @@ static inline void dma_fence_put(struct dma_fence *fence)
/**
* dma_fence_get - increases refcount of the fence
* @fence: [in] fence to increase refcount of
* @fence: fence to increase refcount of
*
* Returns the same fence, with refcount increased by 1.
*/
......@@ -213,7 +281,7 @@ static inline struct dma_fence *dma_fence_get(struct dma_fence *fence)
/**
* dma_fence_get_rcu - get a fence from a reservation_object_list with
* rcu read lock
* @fence: [in] fence to increase refcount of
* @fence: fence to increase refcount of
*
* Function returns NULL if no refcount could be obtained, or the fence.
*/
......@@ -227,7 +295,7 @@ static inline struct dma_fence *dma_fence_get_rcu(struct dma_fence *fence)
/**
* dma_fence_get_rcu_safe - acquire a reference to an RCU tracked fence
* @fencep: [in] pointer to fence to increase refcount of
* @fencep: pointer to fence to increase refcount of
*
* Function returns NULL if no refcount could be obtained, or the fence.
* This function handles acquiring a reference to a fence that may be
......@@ -289,14 +357,16 @@ void dma_fence_enable_sw_signaling(struct dma_fence *fence);
/**
* dma_fence_is_signaled_locked - Return an indication if the fence
* is signaled yet.
* @fence: [in] the fence to check
* @fence: the fence to check
*
* Returns true if the fence was already signaled, false if not. Since this
* function doesn't enable signaling, it is not guaranteed to ever return
* true if dma_fence_add_callback, dma_fence_wait or
* dma_fence_enable_sw_signaling haven't been called before.
* true if dma_fence_add_callback(), dma_fence_wait() or
* dma_fence_enable_sw_signaling() haven't been called before.
*
* This function requires fence->lock to be held.
* This function requires &dma_fence.lock to be held.
*
* See also dma_fence_is_signaled().
*/
static inline bool
dma_fence_is_signaled_locked(struct dma_fence *fence)
......@@ -314,17 +384,19 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
/**
* dma_fence_is_signaled - Return an indication if the fence is signaled yet.
* @fence: [in] the fence to check
* @fence: the fence to check
*
* Returns true if the fence was already signaled, false if not. Since this
* function doesn't enable signaling, it is not guaranteed to ever return
* true if dma_fence_add_callback, dma_fence_wait or
* dma_fence_enable_sw_signaling haven't been called before.
* true if dma_fence_add_callback(), dma_fence_wait() or
* dma_fence_enable_sw_signaling() haven't been called before.
*
* It's recommended for seqno fences to call dma_fence_signal when the
* operation is complete, it makes it possible to prevent issues from
* wraparound between time of issue and time of use by checking the return
* value of this function before calling hardware-specific wait instructions.
*
* See also dma_fence_is_signaled_locked().
*/
static inline bool
dma_fence_is_signaled(struct dma_fence *fence)
......@@ -342,8 +414,8 @@ dma_fence_is_signaled(struct dma_fence *fence)
/**
* __dma_fence_is_later - return if f1 is chronologically later than f2
* @f1: [in] the first fence's seqno
* @f2: [in] the second fence's seqno from the same context
* @f1: the first fence's seqno
* @f2: the second fence's seqno from the same context
*
* Returns true if f1 is chronologically later than f2. Both fences must be
* from the same context, since a seqno is not common across contexts.
......@@ -355,8 +427,8 @@ static inline bool __dma_fence_is_later(u32 f1, u32 f2)
/**
* dma_fence_is_later - return if f1 is chronologically later than f2
* @f1: [in] the first fence from the same context
* @f2: [in] the second fence from the same context
* @f1: the first fence from the same context
* @f2: the second fence from the same context
*
* Returns true if f1 is chronologically later than f2. Both fences must be
* from the same context, since a seqno is not re-used across contexts.
......@@ -372,8 +444,8 @@ static inline bool dma_fence_is_later(struct dma_fence *f1,
/**
* dma_fence_later - return the chronologically later fence
* @f1: [in] the first fence from the same context
* @f2: [in] the second fence from the same context
* @f1: the first fence from the same context
* @f2: the second fence from the same context
*
* Returns NULL if both fences are signaled, otherwise the fence that would be
* signaled last. Both fences must be from the same context, since a seqno is
......@@ -398,7 +470,7 @@ static inline struct dma_fence *dma_fence_later(struct dma_fence *f1,
/**
* dma_fence_get_status_locked - returns the status upon completion
* @fence: [in] the dma_fence to query
* @fence: the dma_fence to query
*
* Drivers can supply an optional error status condition before they signal
* the fence (to indicate whether the fence was completed due to an error
......@@ -422,8 +494,8 @@ int dma_fence_get_status(struct dma_fence *fence);
/**
* dma_fence_set_error - flag an error condition on the fence
* @fence: [in] the dma_fence
* @error: [in] the error to store
* @fence: the dma_fence
* @error: the error to store
*
* Drivers can supply an optional error status condition before they signal
* the fence, to indicate that the fence was completed due to an error
......@@ -449,8 +521,8 @@ signed long dma_fence_wait_any_timeout(struct dma_fence **fences,
/**
* dma_fence_wait - sleep until the fence gets signaled
* @fence: [in] the fence to wait on
* @intr: [in] if true, do an interruptible wait
* @fence: the fence to wait on
* @intr: if true, do an interruptible wait
*
* This function will return -ERESTARTSYS if interrupted by a signal,
* or 0 if the fence was signaled. Other error values may be
......@@ -459,6 +531,8 @@ signed long dma_fence_wait_any_timeout(struct dma_fence **fences,
* Performs a synchronous wait on this fence. It is assumed the caller
* directly or indirectly holds a reference to the fence, otherwise the
* fence might be freed before return, resulting in undefined behavior.
*
* See also dma_fence_wait_timeout() and dma_fence_wait_any_timeout().
*/
static inline signed long dma_fence_wait(struct dma_fence *fence, bool intr)
{
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7