From: Alex Deucher alexander.deucher@amd.com
Adds documentation to most of the functions in radeon_fence.c
v2: address Christian's comments: - split common concept description into it's own comment - fix description of intr parameter - Improve description of -EDEADLK error
Signed-off-by: Alex Deucher alexander.deucher@amd.com --- drivers/gpu/drm/radeon/radeon_fence.c | 238 +++++++++++++++++++++++++++++++++ 1 files changed, 238 insertions(+), 0 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_fence.c b/drivers/gpu/drm/radeon/radeon_fence.c index 67f6fa9..32284e7 100644 --- a/drivers/gpu/drm/radeon/radeon_fence.c +++ b/drivers/gpu/drm/radeon/radeon_fence.c @@ -40,6 +40,26 @@ #include "radeon.h" #include "radeon_trace.h"
+/* + * Fences + * Fences mark an event in the GPUs pipeline and are used + * for GPU/CPU synchronization. When the fence is written, + * it is expected that all buffers associated with that fence + * are no longer in use by the associated ring on the GPU and + * that the the relevant GPU caches have been flushed. Whether + * we use a scratch register or memory location depends on the asic + * and whether writeback is enabled. + */ + +/** + * radeon_fence_write - write a fence value + * + * @rdev: radeon_device pointer + * @seq: sequence number to write + * @ring: ring index the fence is associated with + * + * Writes a fence value to memory or a scratch register (all asics). + */ static void radeon_fence_write(struct radeon_device *rdev, u32 seq, int ring) { if (rdev->wb.enabled) { @@ -49,6 +69,15 @@ static void radeon_fence_write(struct radeon_device *rdev, u32 seq, int ring) } }
+/** + * radeon_fence_read - read a fence value + * + * @rdev: radeon_device pointer + * @ring: ring index the fence is associated with + * + * Reads a fence value from memory or a scratch register (all asics). + * Returns the value of the fence read from memory or register. + */ static u32 radeon_fence_read(struct radeon_device *rdev, int ring) { u32 seq = 0; @@ -61,6 +90,16 @@ static u32 radeon_fence_read(struct radeon_device *rdev, int ring) return seq; }
+/** + * radeon_fence_emit - emit a fence on the requested ring + * + * @rdev: radeon_device pointer + * @fence: radeon fence object + * @ring: ring index the fence is associated with + * + * Emits a fence command on the requested ring (all asics). + * Returns 0 on success, -ENOMEM on failure. + */ int radeon_fence_emit(struct radeon_device *rdev, struct radeon_fence **fence, int ring) @@ -79,6 +118,15 @@ int radeon_fence_emit(struct radeon_device *rdev, return 0; }
+/** + * radeon_fence_process - process a fence + * + * @rdev: radeon_device pointer + * @ring: ring index the fence is associated with + * + * Checks the current fence value and wakes the fence queue + * if the sequence number has increased (all asics). + */ void radeon_fence_process(struct radeon_device *rdev, int ring) { uint64_t seq, last_seq; @@ -139,6 +187,13 @@ void radeon_fence_process(struct radeon_device *rdev, int ring) } }
+/** + * radeon_fence_destroy - destroy a fence + * + * @kref: fence kref + * + * Frees the fence object (all asics). + */ static void radeon_fence_destroy(struct kref *kref) { struct radeon_fence *fence; @@ -147,6 +202,20 @@ static void radeon_fence_destroy(struct kref *kref) kfree(fence); }
+/** + * radeon_fence_seq_signaled - check if a fence sequeuce number has signaled + * + * @rdev: radeon device pointer + * @seq: sequence number + * @ring: ring index the fence is associated with + * + * Check if the last singled fence sequnce number is >= the requested + * sequence number (all asics). + * Returns true if the fence has signaled (current fence value + * is >= requested value) or false if it has not (current fence + * value is < the requested value. Helper function for + * radeon_fence_signaled(). + */ static bool radeon_fence_seq_signaled(struct radeon_device *rdev, u64 seq, unsigned ring) { @@ -161,6 +230,14 @@ static bool radeon_fence_seq_signaled(struct radeon_device *rdev, return false; }
+/** + * radeon_fence_signaled - check if a fence has signaled + * + * @fence: radeon fence object + * + * Check if the requested fence has signaled (all asics). + * Returns true if the fence has signaled or false if it has not. + */ bool radeon_fence_signaled(struct radeon_fence *fence) { if (!fence) { @@ -176,6 +253,24 @@ bool radeon_fence_signaled(struct radeon_fence *fence) return false; }
+/** + * radeon_fence_wait_seq - wait for a specific sequence number + * + * @rdev: radeon device pointer + * @target_seq: sequence number we want to wait for + * @ring: ring index the fence is associated with + * @intr: use interruptable sleep + * @lock_ring: whether the ring should be locked or not + * + * Wait for the requested sequence number to be written (all asics). + * @intr selects whether to use interruptable (true) or non-interruptable + * (false) sleep when waiting for the sequence number. Helper function + * for radeon_fence_wait(), et al. + * Returns 0 if the sequence number has passed, error for all other cases. + * -EDEADLK is returned when a GPU lockup has been detected and the ring is + * marked as not ready so no further jobs get scheduled until a successful + * reset. + */ static int radeon_fence_wait_seq(struct radeon_device *rdev, u64 target_seq, unsigned ring, bool intr, bool lock_ring) { @@ -271,6 +366,17 @@ static int radeon_fence_wait_seq(struct radeon_device *rdev, u64 target_seq, return 0; }
+/** + * radeon_fence_wait - wait for a fence to signal + * + * @fence: radeon fence object + * @intr: use interruptable sleep + * + * Wait for the requested fence to signal (all asics). + * @intr selects whether to use interruptable (true) or non-interruptable + * (false) sleep when waiting for the fence. + * Returns 0 if the fence has passed, error for all other cases. + */ int radeon_fence_wait(struct radeon_fence *fence, bool intr) { int r; @@ -301,6 +407,20 @@ static bool radeon_fence_any_seq_signaled(struct radeon_device *rdev, u64 *seq) return false; }
+/** + * radeon_fence_wait_any_seq - wait for a sequence number on any ring + * + * @rdev: radeon device pointer + * @target_seq: sequence number(s) we want to wait for + * @intr: use interruptable sleep + * + * Wait for the requested sequence number(s) to be written by any ring + * (all asics). Sequnce number array is indexed by ring id. + * @intr selects whether to use interruptable (true) or non-interruptable + * (false) sleep when waiting for the sequence number. Helper function + * for radeon_fence_wait_any(), et al. + * Returns 0 if the sequence number has passed, error for all other cases. + */ static int radeon_fence_wait_any_seq(struct radeon_device *rdev, u64 *target_seq, bool intr) { @@ -410,6 +530,19 @@ static int radeon_fence_wait_any_seq(struct radeon_device *rdev, return 0; }
+/** + * radeon_fence_wait_any - wait for a fence to signal on any ring + * + * @rdev: radeon device pointer + * @fences: radeon fence object(s) + * @intr: use interruptable sleep + * + * Wait for any requested fence to signal (all asics). Fence + * array is indexed by ring id. @intr selects whether to use + * interruptable (true) or non-interruptable (false) sleep when + * waiting for the fences. Used by the suballocator. + * Returns 0 if any fence has passed, error for all other cases. + */ int radeon_fence_wait_any(struct radeon_device *rdev, struct radeon_fence **fences, bool intr) @@ -440,6 +573,15 @@ int radeon_fence_wait_any(struct radeon_device *rdev, return 0; }
+/** + * radeon_fence_wait_next_locked - wait for the next fence to signal + * + * @rdev: radeon device pointer + * @ring: ring index the fence is associated with + * + * Wait for the next fence on the requested ring to signal (all asics). + * Returns 0 if the next fence has passed, error for all other cases. + */ int radeon_fence_wait_next_locked(struct radeon_device *rdev, int ring) { uint64_t seq; @@ -457,6 +599,15 @@ int radeon_fence_wait_next_locked(struct radeon_device *rdev, int ring) return radeon_fence_wait_seq(rdev, seq, ring, false, false); }
+/** + * radeon_fence_wait_empty_locked - wait for all fences to signal + * + * @rdev: radeon device pointer + * @ring: ring index the fence is associated with + * + * Wait for all fences on the requested ring to signal (all asics). + * Returns 0 if the fences have passed, error for all other cases. + */ int radeon_fence_wait_empty_locked(struct radeon_device *rdev, int ring) { /* We are not protected by ring lock when reading current seq @@ -468,12 +619,27 @@ int radeon_fence_wait_empty_locked(struct radeon_device *rdev, int ring) ring, false, false); }
+/** + * radeon_fence_ref - take a ref on a fence + * + * @fence: radeon fence object + * + * Take a reference on a fence (all asics). + * Returns the fence. + */ struct radeon_fence *radeon_fence_ref(struct radeon_fence *fence) { kref_get(&fence->kref); return fence; }
+/** + * radeon_fence_unref - remove a ref on a fence + * + * @fence: radeon fence object + * + * Remove a reference on a fence (all asics). + */ void radeon_fence_unref(struct radeon_fence **fence) { struct radeon_fence *tmp = *fence; @@ -484,6 +650,16 @@ void radeon_fence_unref(struct radeon_fence **fence) } }
+/** + * radeon_fence_count_emitted - get the count of emitted fences + * + * @rdev: radeon device pointer + * @ring: ring index the fence is associated with + * + * Get the number of fences emitted on the requested ring (all asics). + * Returns the number of emitted fences on the ring. Used by the + * dynpm code to ring track activity. + */ unsigned radeon_fence_count_emitted(struct radeon_device *rdev, int ring) { uint64_t emitted; @@ -501,6 +677,17 @@ unsigned radeon_fence_count_emitted(struct radeon_device *rdev, int ring) return (unsigned)emitted; }
+/** + * radeon_fence_need_sync - do we need a semaphore + * + * @fence: radeon fence object + * @dst_ring: which ring to check against + * + * Check if the fence needs to be synced against another ring + * (all asics). If so, we need to emit a semaphore. + * Returns true if we need to sync with another ring, false if + * not. + */ bool radeon_fence_need_sync(struct radeon_fence *fence, int dst_ring) { struct radeon_fence_driver *fdrv; @@ -522,6 +709,15 @@ bool radeon_fence_need_sync(struct radeon_fence *fence, int dst_ring) return true; }
+/** + * radeon_fence_note_sync - record the sync point + * + * @fence: radeon fence object + * @dst_ring: which ring to check against + * + * Note the sequence number at which point the fence will + * be synced with the requested ring (all asics). + */ void radeon_fence_note_sync(struct radeon_fence *fence, int dst_ring) { struct radeon_fence_driver *dst, *src; @@ -546,6 +742,18 @@ void radeon_fence_note_sync(struct radeon_fence *fence, int dst_ring) } }
+/** + * radeon_fence_driver_start_ring - make the fence driver + * ready for use on the requested ring. + * + * @rdev: radeon device pointer + * @ring: ring index to start the fence driver on + * + * Make the fence driver ready for processing (all asics). + * Not all asics have all rings, so each asic will only + * start the fence driver on the rings it has. + * Returns 0 for success, errors for failure. + */ int radeon_fence_driver_start_ring(struct radeon_device *rdev, int ring) { uint64_t index; @@ -574,6 +782,16 @@ int radeon_fence_driver_start_ring(struct radeon_device *rdev, int ring) return 0; }
+/** + * radeon_fence_driver_init_ring - init the fence driver + * for the requested ring. + * + * @rdev: radeon device pointer + * @ring: ring index to start the fence driver on + * + * Init the fence driver for the requested ring (all asics). + * Helper function for radeon_fence_driver_init(). + */ static void radeon_fence_driver_init_ring(struct radeon_device *rdev, int ring) { int i; @@ -588,6 +806,18 @@ static void radeon_fence_driver_init_ring(struct radeon_device *rdev, int ring) rdev->fence_drv[ring].initialized = false; }
+/** + * radeon_fence_driver_init - init the fence driver + * for all possible rings. + * + * @rdev: radeon device pointer + * + * Init the fence driver for all possible rings (all asics). + * Not all asics have all rings, so each asic will only + * start the fence driver on the rings it has using + * radeon_fence_driver_start_ring(). + * Returns 0 for success. + */ int radeon_fence_driver_init(struct radeon_device *rdev) { int ring; @@ -602,6 +832,14 @@ int radeon_fence_driver_init(struct radeon_device *rdev) return 0; }
+/** + * radeon_fence_driver_fini - tear down the fence driver + * for all possible rings. + * + * @rdev: radeon device pointer + * + * Tear down the fence driver for all possible rings (all asics). + */ void radeon_fence_driver_fini(struct radeon_device *rdev) { int ring;