From: Meenakshikumar Somasundaram <meenakshikumar.somasunda...@amd.com>

[ Upstream commit 46fe9cb1a9e62f4e6229f48ae303ef8e6c1fdc64 ]

[Why]
During DP tunnel creation, CM preallocates BW and reduces
estimated BW of other DPIA. CM release preallocation only
when allocation is complete. Display mode validation logic
validates timings based on bw available per host router.
In multi display setup, this causes bw allocation failure
when allocation greater than estimated bw.

[How]
Do zero alloc to make the CM to release preallocation and
update estimated BW correctly for all DPIAs per host router.

Reviewed-by: PeiChen Huang <peichen.hu...@amd.com>
Acked-by: Aurabindo Pillai <aurabindo.pil...@amd.com>
Signed-off-by: Meenakshikumar Somasundaram <meenakshikumar.somasunda...@amd.com>
Tested-by: Daniel Wheeler <daniel.whee...@amd.com>
Signed-off-by: Alex Deucher <alexander.deuc...@amd.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
 .../amd/display/dc/link/protocols/link_dp_dpia_bw.c    | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

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 5491b707cec88..5a965c26bf209 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
@@ -270,7 +270,7 @@ static void set_usb4_req_bw_req(struct dc_link *link, int 
req_bw)
 
        /* Error check whether requested and allocated are equal */
        req_bw = requested_bw * (Kbps_TO_Gbps / 
link->dpia_bw_alloc_config.bw_granularity);
-       if (req_bw == link->dpia_bw_alloc_config.allocated_bw) {
+       if (req_bw && (req_bw == link->dpia_bw_alloc_config.allocated_bw)) {
                DC_LOG_ERROR("%s: Request bw equals to allocated bw for 
link(%d)\n",
                        __func__, link->link_index);
        }
@@ -341,6 +341,14 @@ bool link_dp_dpia_set_dptx_usb4_bw_alloc_support(struct 
dc_link *link)
                        ret = true;
                        init_usb4_bw_struct(link);
                        link->dpia_bw_alloc_config.bw_alloc_enabled = 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
+                        */
+                       link_dp_dpia_allocate_usb4_bandwidth_for_stream(link, 
0);
                }
        }
 
-- 
2.43.0

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