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

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Message-ID: <20251104111339.128685-1-marco.crivellari@suse.com>
Date: Tue,  4 Nov 2025 12:13:39 +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>,
	Andrzej Hajda <andrzej.hajda@...el.com>,
	Robert Foss <rfoss@...nel.org>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Subject: [PATCH] drm/bridge: replace use of system_wq with system_percpu_wq

Currently if a user enqueue 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 consistentcy 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/bridge/ite-it6505.c | 2 +-
 drivers/gpu/drm/bridge/ti-tfp410.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index a094803ba7aa..37bb8123cf9b 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2048,7 +2048,7 @@ static void it6505_start_hdcp(struct it6505 *it6505)
 
 	DRM_DEV_DEBUG_DRIVER(dev, "start");
 	it6505_reset_hdcp(it6505);
-	queue_delayed_work(system_wq, &it6505->hdcp_work,
+	queue_delayed_work(system_percpu_wq, &it6505->hdcp_work,
 			   msecs_to_jiffies(2400));
 }
 
diff --git a/drivers/gpu/drm/bridge/ti-tfp410.c b/drivers/gpu/drm/bridge/ti-tfp410.c
index b80ee089f880..85fa3f8a747e 100644
--- a/drivers/gpu/drm/bridge/ti-tfp410.c
+++ b/drivers/gpu/drm/bridge/ti-tfp410.c
@@ -115,7 +115,7 @@ static void tfp410_hpd_callback(void *arg, enum drm_connector_status status)
 {
 	struct tfp410 *dvi = arg;
 
-	mod_delayed_work(system_wq, &dvi->hpd_work,
+	mod_delayed_work(system_percpu_wq, &dvi->hpd_work,
 			 msecs_to_jiffies(HOTPLUG_DEBOUNCE_MS));
 }
 
-- 
2.51.1