[PATCH 03/23] drm/amd/display: Add DPIA debug option for zero allocation patch

[Alex Hung]

From: Cruise Hung <Cruise.Hung at amd.com>

[WHY & HOW]
The BW zero allocation patch is no longer required.
Add a debug option to enable it in case we encounter an issue.

Reviewed-by: Wenjing Liu <wenjing.liu at amd.com>
Signed-off-by: Cruise Hung <Cruise.Hung at amd.com>
Signed-off-by: Alex Hung <alex.hung at amd.com>
---
 drivers/gpu/drm/amd/display/dc/dc.h            |  3 ++-
 .../dc/link/protocols/link_dp_dpia_bw.c        | 18 ++++++++++--------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index 5c01a535b4fa..83ee6ddaddb7 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -824,7 +824,8 @@ union dpia_debug_options {
 		uint32_t disable_mst_dsc_work_around:1; /* bit 3 */
 		uint32_t enable_force_tbt3_work_around:1; /* bit 4 */
 		uint32_t disable_usb4_pm_support:1; /* bit 5 */
-		uint32_t reserved:26;
+		uint32_t enable_usb4_bw_zero_alloc_patch:1; /* bit 6 */
+		uint32_t reserved:25;
 	} bits;
 	uint32_t raw;
 };
diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c
index 3af7564a84f1..642feac5a673 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_dpia_bw.c
@@ -304,14 +304,16 @@ bool link_dpia_enable_usb4_dp_bw_alloc_mode(struct dc_link *link)
 			link->dpia_bw_alloc_config.bw_alloc_enabled = true;
 			ret = true;
 
-			/*
-			 * During DP tunnel creation, CM preallocates BW and reduces estimated BW of other
-			 * DPIA. CM release preallocation only when allocation is complete. Do zero alloc
-			 * to make the CM to release preallocation and update estimated BW correctly for
-			 * all DPIAs per host router
-			 */
-			// TODO: Zero allocation can be removed once the MSFT CM fix has been released
-			link_dp_dpia_allocate_usb4_bandwidth_for_stream(link, 0);
+			if (link->dc->debug.dpia_debug.bits.enable_usb4_bw_zero_alloc_patch) {
+				/*
+				 * During DP tunnel creation, the CM preallocates BW
+				 * and reduces the estimated BW of other DPIAs.
+				 * The CM releases the preallocation only when the allocation is complete.
+				 * Perform a zero allocation to make the CM release the preallocation
+				 * and correctly update the estimated BW for all DPIAs per host router.
+				 */
+				link_dp_dpia_allocate_usb4_bandwidth_for_stream(link, 0);
+			}
 		} else
 			DC_LOG_DEBUG("%s:  link[%d] failed to enable DPTX BW allocation mode", __func__, link->link_index);
 	}
-- 
2.43.0