linux-kernel - [PATCH] drm/i915/gsc: mei interrupt top half should be in irq disabled context

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Message-Id: <20250425060455.641008-1-junxiao.chang@intel.com>
Date: Fri, 25 Apr 2025 14:04:54 +0800
From: Junxiao Chang <junxiao.chang@...el.com>
To: tomas.winkler@...el.com,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Clark Williams <clrkwllms@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Daniele Ceraolo Spurio <daniele.ceraolospurio@...el.com>,
	Vitaly Lubart <vitaly.lubart@...el.com>,
	Alexander Usyskin <alexander.usyskin@...el.com>,
	intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	linux-rt-devel@...ts.linux.dev
Cc: junxiao.chang@...el.com,
	furong.zhou@...el.com
Subject: [PATCH] drm/i915/gsc: mei interrupt top half should be in irq disabled context

MEI GSC interrupt comes from i915. It has top half and bottom half.
Top half is called from i915 interrupt handler. It should be in
irq disabled context.

With RT kernel, by default i915 IRQ handler is in threaded IRQ. MEI GSC
top half might be in threaded IRQ context. generic_handle_irq_safe API
could be called from either IRQ or process context, it disables local
IRQ then calls MEI GSC interrupt top half.

This change fixes A380/A770 GPU boot hang issue with RT kernel.

Fixes: 1e3dc1d8622b ("drm/i915/gsc: add gsc as a mei auxiliary device")
Tested-by: Furong Zhou <furong.zhou@...el.com>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Signed-off-by: Junxiao Chang <junxiao.chang@...el.com>
---
 drivers/gpu/drm/i915/gt/intel_gsc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_gsc.c b/drivers/gpu/drm/i915/gt/intel_gsc.c
index 1e925c75fb080..a099d885508ac 100644
--- a/drivers/gpu/drm/i915/gt/intel_gsc.c
+++ b/drivers/gpu/drm/i915/gt/intel_gsc.c
@@ -284,7 +284,9 @@ static void gsc_irq_handler(struct intel_gt *gt, unsigned int intf_id)
 	if (gt->gsc.intf[intf_id].irq < 0)
 		return;
 
-	ret = generic_handle_irq(gt->gsc.intf[intf_id].irq);
+	/* It can be called in both irq context and in thread context */
+	ret = generic_handle_irq_safe(gt->gsc.intf[intf_id].irq);
+
 	if (ret)
 		gt_err_ratelimited(gt, "error handling GSC irq: %d\n", ret);
 }
-- 
2.34.1