[PATCH 19/21] drm/i915/gt: document TLB cache invalidation functions

[Mauro Carvalho Chehab <mchehab@kernel.org>]

Add a description for the kAPI functions inside intel_tlb.c.

Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
---

See [PATCH 00/21] at: https://lore.kernel.org/all/cover.1657703926.git.mchehab@kernel.org/

 drivers/gpu/drm/i915/gt/intel_tlb.c | 36 +++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_tlb.c b/drivers/gpu/drm/i915/gt/intel_tlb.c
index 15ed83226676..aa2e0086ae88 100644
--- a/drivers/gpu/drm/i915/gt/intel_tlb.c
+++ b/drivers/gpu/drm/i915/gt/intel_tlb.c
@@ -146,6 +146,18 @@ static void mmio_invalidate_full(struct intel_gt *gt)
 	intel_uncore_forcewake_put_delayed(uncore, FORCEWAKE_ALL);
 }
 
+/**
+ * intel_gt_invalidate_tlb_full - do full TLB cache invalidation
+ * @gt: GT structure
+ * @seqno: sequence number
+ *
+ * Do a full TLB cache invalidation if the @seqno is bigger than the last
+ * full TLB cache invalidation.
+ *
+ * Note:
+ * The TLB cache invalidation logic depends on GEN-specific registers.
+ * It currently supports GEN8 to GEN12 and GuC-based TLB cache invalidation.
+ */
 void intel_gt_invalidate_tlb_full(struct intel_gt *gt, u32 seqno)
 {
 	intel_wakeref_t wakeref;
@@ -220,6 +232,17 @@ static bool mmio_invalidate_range(struct intel_gt *gt, u64 start, u64 length)
 	return err == 0;
 }
 
+/**
+ * intel_gt_invalidate_tlb_range - do full TLB cache invalidation
+ * @gt: GT structure
+ * @start: range start
+ * @length: range length
+ *
+ * Do a selected TLB cache invalidation on a range pointed by @start
+ * with @length size.
+ *
+ * Only some GuC-based GPUs can do a selective cache invalidation.
+ */
 bool intel_gt_invalidate_tlb_range(struct intel_gt *gt,
 				   u64 start, u64 length)
 {
@@ -247,12 +270,25 @@ bool intel_gt_invalidate_tlb_range(struct intel_gt *gt,
 	return true;
 }
 
+/**
+ * intel_gt_init_tlb - initialize TLB-specific vars
+ * @gt: GT structure
+ *
+ * TLB cache invalidation logic internally uses some resources that require
+ * initialization. Should be called before doing any TLB cache invalidation.
+ */
 void intel_gt_init_tlb(struct intel_gt *gt)
 {
 	mutex_init(&gt->tlb.invalidate_lock);
 	seqcount_mutex_init(&gt->tlb.seqno, &gt->tlb.invalidate_lock);
 }
 
+/**
+ * intel_gt_fini_tlb - initialize TLB-specific vars
+ * @gt: GT structure
+ *
+ * Frees any resources needed by TLB cache invalidation logic.
+ */
 void intel_gt_fini_tlb(struct intel_gt *gt)
 {
 	mutex_destroy(&gt->tlb.invalidate_lock);
-- 
2.36.1