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

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Message-ID: <aGLV9YL3EWXuf_Kk@intel.com>
Date: Mon, 30 Jun 2025 14:22:45 -0400
From: Rodrigo Vivi <rodrigo.vivi@...el.com>
To: Junxiao Chang <junxiao.chang@...el.com>
CC: <tomas.winkler@...el.com>, Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.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>,
	<furong.zhou@...el.com>
Subject: Re: [PATCH] drm/i915/gsc: mei interrupt top half should be in irq
 disabled context

On Fri, Apr 25, 2025 at 11:11:07PM +0800, Junxiao Chang wrote:
> 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 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_gsc.c b/drivers/gpu/drm/i915/gt/intel_gsc.c
> index 1e925c75fb080..c43febc862dc3 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gsc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_gsc.c
> @@ -284,7 +284,7 @@ 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);
> +	ret = generic_handle_irq_safe(gt->gsc.intf[intf_id].irq);


Reviewed-by: Rodrigo Vivi <rodrigo.vivi@...el.com>
and pushed to drm-intel-gt-next

>  	if (ret)
>  		gt_err_ratelimited(gt, "error handling GSC irq: %d\n", ret);
>  }
> -- 
> 2.34.1
>