linux-kernel - Re: [PATCH v1 3/3] usb: typec: fusb302: Switch to threaded interrupt handler

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Message-ID: <CACpCAL0GLMV-2p1tKAXe6R+N2c4YadH9vpEG3GdPoHTNTQSuow@mail.gmail.com>
Date: Wed, 7 Jan 2026 17:52:38 +0800
From: 张永波 <giraffesnn123@...il.com>
To: Hans de Goede <hansg@...nel.org>
Cc: Anand Moon <linux.amoon@...il.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Heiko Stuebner <heiko@...ech.de>, Heikki Krogerus <heikki.krogerus@...ux.intel.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Sebastian Reichel <sebastian.reichel@...labora.com>, FUKAUMI Naoki <naoki@...xa.com>, 
	Nicolas Frattaroli <nicolas.frattaroli@...labora.com>, 
	Cristian Ciocaltea <cristian.ciocaltea@...labora.com>, 
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@...r.kernel.org>, 
	"moderated list:ARM/Rockchip SoC support" <linux-arm-kernel@...ts.infradead.org>, 
	"open list:ARM/Rockchip SoC support" <linux-rockchip@...ts.infradead.org>, 
	open list <linux-kernel@...r.kernel.org>, 
	"open list:USB TYPEC CLASS" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v1 3/3] usb: typec: fusb302: Switch to threaded interrupt handler

> Still ideally we would solve this in another way then
> switching to a threaded IRQ handler.
>
> As the commit message of the mei-vsc fix mentions
> the root cause of these errors is typically an interrupt
> chip driver which uses IRQF_NO_THREAD disabling the auto
> threading of all interrupt handlers in RT mode.
>
> So the first question here would be to see if that flag is
> used in the interrupt chip and if yes, is that flag really
> necessary ?
This is very similar to the issue addressed in commit 24b176d8827d
("drm/msm/dsi: Remove spurious IRQF_ONESHOT flag").
The IRQF_ONESHOT flag is preventing forced threading here.

In irq_setup_forced_threading(), the conversion to threaded interrupts
is explicitly skipped if any of the IRQF_NO_THREAD, IRQF_PERCPU,
or IRQF_ONESHOT flags are present. In this case, IRQF_ONESHOT
appears to be the reason.

Regards,
giraffesnn