diff mbox series

[23/30] drm/amd/display: Fix link training fallback logic

Message ID	20211122183418.73674-24-tjaalton@ubuntu.com
State	New
Headers	show Return-Path: <kernel-team-bounces@lists.ubuntu.com> From: Timo Aaltonen <tjaalton@ubuntu.com> To: kernel-team@lists.ubuntu.com Subject: [PATCH 23/30] drm/amd/display: Fix link training fallback logic Date: Mon, 22 Nov 2021 20:34:11 +0200 Message-Id: <20211122183418.73674-24-tjaalton@ubuntu.com> In-Reply-To: <20211122183418.73674-1-tjaalton@ubuntu.com> References: <20211122183418.73674-1-tjaalton@ubuntu.com> MIME-Version: 1.0 Precedence: list Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" <kernel-team-bounces@lists.ubuntu.com>
Series	drm/amdgpu: Add USB4 support for DP tunneling \| expand [J,v2,00/30] drm/amdgpu: Add USB4 support for DP tunneling [01/30] drm/amd/display: Support for DMUB HPD interrupt handling [02/30] drm/amd/display: Update link encoder object creation. [03/30] drm/amd/display: USB4 DPIA enumeration and AUX Tunneling [04/30] drm/amd/display: Support for DMUB HPD and HPD RX interrupt handling [05/30] drm/amd/display: Set DPIA link endpoint type [06/30] drm/amd/display: Stub out DPIA link training call [07/30] drm/amd/display: Add stub to get DPIA tunneling device data [08/30] drm/amd/display: Skip DPCD read for DPTX-to-DPIA hop [09/30] drm/amd/display: Train DPIA links with fallback [10/30] drm/amd/display: Implement DPIA training loop [11/30] drm/amd/display: Implement DPIA link configuration [12/30] drm/amd/display: Implement DPIA clock recovery phase [13/30] drm/amd/display: Implement DPIA equalisation phase [14/30] drm/amd/display: Implement end of training for hop in DPIA display path [15/30] drm/amd/display: Support for SET_CONFIG processing with DMUB [16/30] drm/amd/display: isolate link training setting override to its own function [17/30] drm/amd/display: Read USB4 DP tunneling data from DPCD. [18/30] drm/amd/display: Add dpia debug options [19/30] drm/amd/display: Support for SET_CONFIG processing with DMUB [20/30] drm/amd/display: Add DPCD writes at key points [21/30] drm/amd/display: Fix DIG_HPD_SELECT for USB4 display endpoints. [22/30] drm/amd/display: Add helper for blanking all dp displays [23/30] drm/amd/display: Fix link training fallback logic [24/30] drm/amd/display: Add debug flags for USB4 DP link training. [25/30] drm/amd/display: Fix dynamic link encoder access. [26/30] drm/amd/display: Fix concurrent dynamic encoder assignment [27/30] drm/amd/display: Fix dynamic encoder reassignment [28/30] drm/amd/display: Fix for access for ddc pin and aux engine. [29/30] drm/amd/display: Deadlock/HPD Status/Crash Bug Fix [30/30] drm/amd/display: Fix USB4 Aux via DMUB terminate unexpectedly

Commit Message

Timo Aaltonen Nov. 22, 2021, 6:34 p.m. UTC

From: Jimmy Kizito <Jimmy.Kizito@amd.com>

BugLink: https://bugs.launchpad.net/bugs/1951868

[Why]
Link training should fail if stream bandwidth exceeds link bandwidth.

[How]
Correct fallback logic and use named variables to make intention clear.

Reviewed-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 4de0bfe67bc98fb2a1115bc58ef3b9bc21717629)
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff mbox series

Patch

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index af721ded8458..350cd7e1e515 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -1891,12 +1891,16 @@  bool perform_link_training_with_retries(
 			if (type == dc_connection_none)
 				break;
 		} else if (do_fallback) {
+			uint32_t req_bw;
+			uint32_t link_bw;
+
 			decide_fallback_link_setting(*link_setting, &current_setting, status);
 			/* Fail link training if reduced link bandwidth no longer meets
 			 * stream requirements.
 			 */
-			if (dc_bandwidth_in_kbps_from_timing(&stream->timing) <
-					dc_link_bandwidth_kbps(link, &current_setting))
+			req_bw = dc_bandwidth_in_kbps_from_timing(&stream->timing);
+			link_bw = dc_link_bandwidth_kbps(link, &current_setting);
+			if (req_bw > link_bw)
 				break;
 		}