linux-kernel - [PATCH] drm/vc4: hdmi: replace use of system_wq with system_percpu

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Message-ID: <20251105101134.82064-1-marco.crivellari@suse.com>
Date: Wed,  5 Nov 2025 11:11:34 +0100
From: Marco Crivellari <marco.crivellari@...e.com>
To: linux-kernel@...r.kernel.org,
	dri-devel@...ts.freedesktop.org
Cc: Tejun Heo <tj@...nel.org>,
	Lai Jiangshan <jiangshanlai@...il.com>,
	Frederic Weisbecker <frederic@...nel.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Marco Crivellari <marco.crivellari@...e.com>,
	Michal Hocko <mhocko@...e.com>,
	Maxime Ripard <mripard@...nel.org>,
	Dave Stevenson <dave.stevenson@...pberrypi.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Subject: [PATCH] drm/vc4: hdmi: replace use of system_wq with system_percpu_wq

Currently if a user enqueues a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistency cannot be addressed without refactoring the API.

This patch continues the effort to refactor worqueue APIs, which has begun
with the change introducing new workqueues and a new alloc_workqueue flag:

commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")

system_wq should be the per-cpu workqueue, yet in this name nothing makes
that clear, so replace system_wq with system_percpu_wq.

The old wq (system_wq) will be kept for a few release cycles.

Suggested-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 07c91b450f93..c39cf1530f23 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -745,7 +745,7 @@ static void vc4_hdmi_enable_scrambling(struct drm_encoder *encoder)
 
 	vc4_hdmi->scdc_enabled = true;
 
-	queue_delayed_work(system_wq, &vc4_hdmi->scrambling_work,
+	queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
 			   msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
 }
 
@@ -794,7 +794,7 @@ static void vc4_hdmi_scrambling_wq(struct work_struct *work)
 	drm_scdc_set_high_tmds_clock_ratio(connector, true);
 	drm_scdc_set_scrambling(connector, true);
 
-	queue_delayed_work(system_wq, &vc4_hdmi->scrambling_work,
+	queue_delayed_work(system_percpu_wq, &vc4_hdmi->scrambling_work,
 			   msecs_to_jiffies(SCRAMBLING_POLLING_DELAY_MS));
 }
 
-- 
2.51.1