linux-kernel - Re: [PATCH 1/4] drm: adp: Use spin_lock_irqsave for drm device event

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Message-ID: <aAAZZjM5rA1_ON0e@blossom>
Date: Wed, 16 Apr 2025 16:56:06 -0400
From: Alyssa Rosenzweig <alyssa@...enzweig.io>
To: j@...nau.net
Cc: Sasha Finkelstein <fnkl.kernel@...il.com>,
	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>,
	Neal Gompa <neal@...pa.dev>, Dmitry Baryshkov <lumag@...nel.org>,
	dri-devel@...ts.freedesktop.org, asahi@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] drm: adp: Use spin_lock_irqsave for drm device
 event_lock

Reviewed-by: Alyssa Rosenzweig <alyssa@...enzweig.io>

Le Wed , Apr 16, 2025 at 10:25:27PM +0200, Janne Grunau via B4 Relay a écrit :
> From: Janne Grunau <j@...nau.net>
> 
> The lock is used in the interrupt handler so use spin_lock_irqsave to
> disable interrupts and avoid deadlocks with the irq handler.
> 
> Fixes: 332122eba628 ("drm: adp: Add Apple Display Pipe driver")
> Signed-off-by: Janne Grunau <j@...nau.net>
> ---
>  drivers/gpu/drm/adp/adp_drv.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/adp/adp_drv.c b/drivers/gpu/drm/adp/adp_drv.c
> index c98c647f981d5383149647126762a5cdec8f4e4b..157298a8ff42b95275411dd4a7a0c70780fd86fd 100644
> --- a/drivers/gpu/drm/adp/adp_drv.c
> +++ b/drivers/gpu/drm/adp/adp_drv.c
> @@ -310,6 +310,7 @@ static void adp_crtc_atomic_flush(struct drm_crtc *crtc,
>  				  struct drm_atomic_state *state)
>  {
>  	u32 frame_num = 1;
> +	unsigned long flags;
>  	struct adp_drv_private *adp = crtc_to_adp(crtc);
>  	struct drm_crtc_state *new_state = drm_atomic_get_new_crtc_state(state, crtc);
>  	u64 new_size = ALIGN(new_state->mode.hdisplay *
> @@ -330,13 +331,13 @@ static void adp_crtc_atomic_flush(struct drm_crtc *crtc,
>  	}
>  	writel(ADBE_FIFO_SYNC | frame_num, adp->be + ADBE_FIFO);
>  	//FIXME: use adbe flush interrupt
> -	spin_lock_irq(&crtc->dev->event_lock);
> +	spin_lock_irqsave(&crtc->dev->event_lock, flags);
>  	if (crtc->state->event) {
>  		drm_crtc_vblank_get(crtc);
>  		adp->event = crtc->state->event;
>  	}
>  	crtc->state->event = NULL;
> -	spin_unlock_irq(&crtc->dev->event_lock);
> +	spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
>  }
>  
>  static const struct drm_crtc_funcs adp_crtc_funcs = {
> 
> -- 
> 2.49.0
> 
>