linux-kernel - [PATCH v3] drm/amd/display: add an ASSERT() to irq service functions

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Date:   Mon, 17 Oct 2022 12:13:22 -0400
From:   Hamza Mahfooz <hamza.mahfooz@....com>
To:     <amd-gfx@...ts.freedesktop.org>
CC:     Roman Li <roman.li@....com>, Hamza Mahfooz <hamza.mahfooz@....com>,
        "Harry Wentland" <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        "Rodrigo Siqueira" <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Mario Limonciello <mario.limonciello@....com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Stylon Wang <stylon.wang@....com>,
        Alex Hung <alex.hung@....com>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] drm/amd/display: add an ASSERT() to irq service functions

Currently, if we encounter unimplemented functions, it is difficult to
tell what caused them just by looking at dmesg and that is compounded by
the fact that it is often hard to reproduce said issues, for instance we
have had reports of this condition being triggered when removing a
secondary display that is setup in mirror mode and is connected using
usb-c. So, to have access to more detailed debugging information, add an
ASSERT() to dal_irq_service_ack() and dal_irq_service_set() that only
triggers when we encounter an unimplemented function.

Signed-off-by: Hamza Mahfooz <hamza.mahfooz@....com>
---
v2: detail specific instance that I'm interested in and use ASSERT()
    instead of WARN().

v3: move ASSERT()s inside the new if blocks.
---
 .../gpu/drm/amd/display/dc/irq/irq_service.c    | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
index 7bad39bba86b..d100edaedbbb 100644
--- a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
+++ b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
@@ -112,8 +112,15 @@ bool dal_irq_service_set(
 
 	dal_irq_service_ack(irq_service, source);
 
-	if (info->funcs && info->funcs->set)
+	if (info->funcs && info->funcs->set) {
+		if (info->funcs->set == dal_irq_service_dummy_set) {
+			DC_LOG_WARNING("%s: src: %d, st: %d\n", __func__,
+				       source, enable);
+			ASSERT(0);
+		}
+
 		return info->funcs->set(irq_service, info, enable);
+	}
 
 	dal_irq_service_set_generic(irq_service, info, enable);
 
@@ -146,8 +153,14 @@ bool dal_irq_service_ack(
 		return false;
 	}
 
-	if (info->funcs && info->funcs->ack)
+	if (info->funcs && info->funcs->ack) {
+		if (info->funcs->ack == dal_irq_service_dummy_ack) {
+			DC_LOG_WARNING("%s: src: %d\n", __func__, source);
+			ASSERT(0);
+		}
+
 		return info->funcs->ack(irq_service, info);
+	}
 
 	dal_irq_service_ack_generic(irq_service, info);
 
-- 
2.38.0