drm/xe/lrc: Add table with LRC layout

Add a table to document the LRC's BO layout to make it easier to
visualize how each region stacks on top of each other.

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Link: https://lore.kernel.org/r/20250710-lrc-refactors-v2-4-a5e2ca03f6bd@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
index 3a169011a2ad2b21abda87eddfa7782cf3f134da..6d38411bdebaadee9db7e2d387c028a2710320ae 100644 (file)
--- a/drivers/gpu/drm/xe/xe_lrc.c
+++ b/drivers/gpu/drm/xe/xe_lrc.c
@@ -43,6 +43,30 @@
 #define LRC_INDIRECT_RING_STATE_SIZE           SZ_4K
 #define LRC_WA_BB_SIZE                         SZ_4K
 
+/*
+ * Layout of the LRC and associated data allocated as
+ * lrc->bo:
+ *
+ *   Region                       Size
+ *  +============================+=================================+ <- __xe_lrc_ring_offset()
+ *  | Ring                       | ring_size, see                  |
+ *  |                            | xe_lrc_init()                   |
+ *  +============================+=================================+ <- __xe_lrc_pphwsp_offset()
+ *  | PPHWSP (includes SW state) | 4K                              |
+ *  +----------------------------+---------------------------------+ <- __xe_lrc_regs_offset()
+ *  | Engine Context Image       | n * 4K, see                     |
+ *  |                            | xe_gt_lrc_size()                |
+ *  +----------------------------+---------------------------------+ <- __xe_lrc_indirect_ring_offset()
+ *  | Indirect Ring State Page   | 0 or 4k, see                    |
+ *  |                            | XE_LRC_FLAG_INDIRECT_RING_STATE |
+ *  +============================+=================================+ <- __xe_lrc_indirect_ctx_offset()
+ *  | Indirect Context Page      | 0 or 4k, see                    |
+ *  |                            | XE_LRC_FLAG_INDIRECT_CTX        |
+ *  +============================+=================================+ <- __xe_lrc_wa_bb_offset()
+ *  | WA BB Per Ctx              | 4k                              |
+ *  +============================+=================================+ <- xe_bo_size(lrc->bo)
+ */
+
 static struct xe_device *
 lrc_to_xe(struct xe_lrc *lrc)
 {