From: Alex Deucher alexander.deucher@amd.com
Adds documentation to most of the functions in radeon_ring.c
v2: adjust per Christian's suggestions v3: adjust per Christian's latest patches v4: adjust per my latest changes
Signed-off-by: Alex Deucher alexander.deucher@amd.com --- drivers/gpu/drm/radeon/radeon_ring.c | 208 +++++++++++++++++++++++++++++++++- 1 files changed, 205 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_ring.c b/drivers/gpu/drm/radeon/radeon_ring.c index c1efde6..f2fc25d 100644 --- a/drivers/gpu/drm/radeon/radeon_ring.c +++ b/drivers/gpu/drm/radeon/radeon_ring.c @@ -35,10 +35,28 @@ #include "atom.h"
/* - * IB. + * IB + * IBs (Indirect Buffers) and areas of GPU accessible memory where + * commands are stored. You can put a pointer to the IB in the + * command ring and the hw will fetch the commands from the IB + * and execute them. Generally userspace acceleration drivers + * produce command buffers which are send to the kernel and + * put in IBs for execution by the requested ring. */ int radeon_debugfs_sa_init(struct radeon_device *rdev);
+/** + * radeon_ib_get - request an IB (Indirect Buffer) + * + * @rdev: radeon_device pointer + * @ring: ring index the IB is associated with + * @ib: IB object returned + * @size: requested IB size + * + * Request an IB (all asics). IBs are allocated using the + * suballocator. + * Returns 0 on success, error on failure. + */ int radeon_ib_get(struct radeon_device *rdev, int ring, struct radeon_ib *ib, unsigned size) { @@ -67,6 +85,14 @@ int radeon_ib_get(struct radeon_device *rdev, int ring, return 0; }
+/** + * radeon_ib_free - free an IB (Indirect Buffer) + * + * @rdev: radeon_device pointer + * @ib: IB object to free + * + * Free an IB (all asics). + */ void radeon_ib_free(struct radeon_device *rdev, struct radeon_ib *ib) { radeon_semaphore_free(rdev, &ib->semaphore, ib->fence); @@ -74,6 +100,26 @@ void radeon_ib_free(struct radeon_device *rdev, struct radeon_ib *ib) radeon_fence_unref(&ib->fence); }
+/** + * radeon_ib_schedule - schedule an IB (Indirect Buffer) on the ring + * + * @rdev: radeon_device pointer + * @ib: IB object to schedule + * @const_ib: Const IB to schedule (SI only) + * + * Schedule an IB on the associated ring (all asics). + * Returns 0 on success, error on failure. + * + * On SI, there are two parallel engines fed from the primary ring, + * the CE (Constant Engine) and the DE (Drawing Engine). Since + * resource descriptors have moved to memory, the CE allows you to + * prime the caches while the DE is updating register state so that + * the resource descriptors will be already in cache when the draw is + * processed. To accomplish this, the userspace driver submits two + * IBs, one for the CE and one for the DE. If there is a CE IB (called + * a CONST_IB), it will be put on the ring prior to the DE IB. Prior + * to SI there was just a DE IB. + */ int radeon_ib_schedule(struct radeon_device *rdev, struct radeon_ib *ib, struct radeon_ib *const_ib) { @@ -124,6 +170,15 @@ int radeon_ib_schedule(struct radeon_device *rdev, struct radeon_ib *ib, return 0; }
+/** + * radeon_ib_pool_init - Init the IB (Indirect Buffer) pool + * + * @rdev: radeon_device pointer + * + * Initialize the suballocator to manage a pool of memory + * for use as IBs (all asics). + * Returns 0 on success, error on failure. + */ int radeon_ib_pool_init(struct radeon_device *rdev) { int r; @@ -150,6 +205,14 @@ int radeon_ib_pool_init(struct radeon_device *rdev) return 0; }
+/** + * radeon_ib_pool_fini - Free the IB (Indirect Buffer) pool + * + * @rdev: radeon_device pointer + * + * Tear down the suballocator managing the pool of memory + * for use as IBs (all asics). + */ void radeon_ib_pool_fini(struct radeon_device *rdev) { if (rdev->ib_pool_ready) { @@ -159,6 +222,16 @@ void radeon_ib_pool_fini(struct radeon_device *rdev) } }
+/** + * radeon_ib_ring_tests - test IBs on the rings + * + * @rdev: radeon_device pointer + * + * Test an IB (Indirect Buffer) on each ring. + * If the test fails, disable the ring. + * Returns 0 on success, error if the primary GFX ring + * IB test fails. + */ int radeon_ib_ring_tests(struct radeon_device *rdev) { unsigned i; @@ -190,10 +263,28 @@ int radeon_ib_ring_tests(struct radeon_device *rdev) }
/* - * Ring. + * Rings + * Most engines on the GPU are fed via ring buffers. Ring + * buffers are areas of GPU accessible memory that the host + * writes commands into and the GPU reads commands out of. + * There is a rptr (read pointer) that determines where the + * GPU is currently reading, and a wptr (write pointer) + * which determines where the host has written. When the + * pointers are equal, the ring is idle. When the host + * writes commands to the ring buffer, it increments the + * wptr. The GPU then starts fetching commands and executes + * them until the pointers are equal again. */ int radeon_debugfs_ring_init(struct radeon_device *rdev, struct radeon_ring *ring);
+/** + * radeon_ring_write - write a value to the ring + * + * @ring: radeon_ring structure holding ring information + * @v: dword (dw) value to write + * + * Write a value to the requested ring buffer (all asics). + */ void radeon_ring_write(struct radeon_ring *ring, uint32_t v) { #if DRM_DEBUG_CODE @@ -207,6 +298,16 @@ void radeon_ring_write(struct radeon_ring *ring, uint32_t v) ring->ring_free_dw--; }
+/** + * radeon_ring_supports_scratch_reg - check if the ring supports + * writing to scratch registers + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * + * Check if a specific ring supports writing to scratch registers (all asics). + * Returns true if the ring supports writing to scratch regs, false if not. + */ bool radeon_ring_supports_scratch_reg(struct radeon_device *rdev, struct radeon_ring *ring) { @@ -220,6 +321,14 @@ bool radeon_ring_supports_scratch_reg(struct radeon_device *rdev, } }
+/** + * radeon_ring_free_size - update the free size + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * + * Update the free dw slots in the ring buffer (all asics). + */ void radeon_ring_free_size(struct radeon_device *rdev, struct radeon_ring *ring) { u32 rptr; @@ -238,7 +347,16 @@ void radeon_ring_free_size(struct radeon_device *rdev, struct radeon_ring *ring) } }
- +/** + * radeon_ring_alloc - allocate space on the ring buffer + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * @ndw: number of dwords to allocate in the ring buffer + * + * Allocate @ndw dwords in the ring buffer (all asics). + * Returns 0 on success, error on failure. + */ int radeon_ring_alloc(struct radeon_device *rdev, struct radeon_ring *ring, unsigned ndw) { int r; @@ -260,6 +378,17 @@ int radeon_ring_alloc(struct radeon_device *rdev, struct radeon_ring *ring, unsi return 0; }
+/** + * radeon_ring_lock - lock the ring and allocate space on it + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * @ndw: number of dwords to allocate in the ring buffer + * + * Lock the ring and allocate @ndw dwords in the ring buffer + * (all asics). + * Returns 0 on success, error on failure. + */ int radeon_ring_lock(struct radeon_device *rdev, struct radeon_ring *ring, unsigned ndw) { int r; @@ -273,6 +402,16 @@ int radeon_ring_lock(struct radeon_device *rdev, struct radeon_ring *ring, unsig return 0; }
+/** + * radeon_ring_commit - tell the GPU to execute the new + * commands on the ring buffer + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * + * Update the wptr (write pointer) to tell the GPU to + * execute new commands on the ring buffer (all asics). + */ void radeon_ring_commit(struct radeon_device *rdev, struct radeon_ring *ring) { /* We pad to match fetch size */ @@ -284,23 +423,55 @@ void radeon_ring_commit(struct radeon_device *rdev, struct radeon_ring *ring) (void)RREG32(ring->wptr_reg); }
+/** + * radeon_ring_unlock_commit - tell the GPU to execute the new + * commands on the ring buffer and unlock it + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * + * Call radeon_ring_commit() then unlock the ring (all asics). + */ void radeon_ring_unlock_commit(struct radeon_device *rdev, struct radeon_ring *ring) { radeon_ring_commit(rdev, ring); mutex_unlock(&rdev->ring_lock); }
+/** + * radeon_ring_undo - reset the wptr + * + * @ring: radeon_ring structure holding ring information + * + * Reset the driver's copy of the wtpr (all asics). + */ void radeon_ring_undo(struct radeon_ring *ring) { ring->wptr = ring->wptr_old; }
+/** + * radeon_ring_unlock_undo - reset the wptr and unlock the ring + * + * @ring: radeon_ring structure holding ring information + * + * Call radeon_ring_undo() then unlock the ring (all asics). + */ void radeon_ring_unlock_undo(struct radeon_device *rdev, struct radeon_ring *ring) { radeon_ring_undo(ring); mutex_unlock(&rdev->ring_lock); }
+/** + * radeon_ring_force_activity - add some nop packets to the ring + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * + * Add some nop packets to the ring to force activity (all asics). + * Used for lockup detection to see if the rptr is advancing. + */ void radeon_ring_force_activity(struct radeon_device *rdev, struct radeon_ring *ring) { int r; @@ -315,6 +486,13 @@ void radeon_ring_force_activity(struct radeon_device *rdev, struct radeon_ring * } }
+/** + * radeon_ring_force_activity - update lockup variables + * + * @ring: radeon_ring structure holding ring information + * + * Update the last rptr value and timestamp (all asics). + */ void radeon_ring_lockup_update(struct radeon_ring *ring) { ring->last_rptr = ring->rptr; @@ -458,6 +636,22 @@ int radeon_ring_restore(struct radeon_device *rdev, struct radeon_ring *ring, return 0; }
+/** + * radeon_ring_init - init driver ring struct. + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * @ring_size: size of the ring + * @rptr_offs: offset of the rptr writeback location in the WB buffer + * @rptr_reg: MMIO offset of the rptr register + * @wptr_reg: MMIO offset of the wptr register + * @ptr_reg_shift: bit offset of the rptr/wptr values + * @ptr_reg_mask: bit mask of the rptr/wptr values + * @nop: nop packet for this ring + * + * Initialize the driver information for the selected ring (all asics). + * Returns 0 on success, error on failure. + */ int radeon_ring_init(struct radeon_device *rdev, struct radeon_ring *ring, unsigned ring_size, unsigned rptr_offs, unsigned rptr_reg, unsigned wptr_reg, u32 ptr_reg_shift, u32 ptr_reg_mask, u32 nop) @@ -511,6 +705,14 @@ int radeon_ring_init(struct radeon_device *rdev, struct radeon_ring *ring, unsig return 0; }
+/** + * radeon_ring_fini - tear down the driver ring struct. + * + * @rdev: radeon_device pointer + * @ring: radeon_ring structure holding ring information + * + * Tear down the driver information for the selected ring (all asics). + */ void radeon_ring_fini(struct radeon_device *rdev, struct radeon_ring *ring) { int r;