linux-kernel - Re: [regression drm/noveau] suspend to ram -> BOOM: exception RIP: drm_calc_vbltimestamp_from

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Date:   Fri, 14 Jul 2017 15:41:33 +0200
From:   Mike Galbraith <efault@....de>
To:     Ilia Mirkin <imirkin@...m.mit.edu>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "nouveau@...ts.freedesktop.org" <nouveau@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Ben Skeggs <bskeggs@...hat.com>
Subject: Re: [regression drm/noveau] suspend to ram -> BOOM: exception RIP:
 drm_calc_vbltimestamp_from_scanoutpos+335

On Fri, 2017-07-14 at 15:36 +0200, Mike Galbraith wrote:
>  All DRM did was to slip a
> WARN_ON_ONCE() that nouveau triggers into a kernel module where such
> things no longer warn, they blow the box out of the water.

BTW, turn that irksome WARN_ON_ONCE() in drivers/gpu/drm/drm_vblank.c
into a WARN_ONCE(), and all is peachy, you get the warning, box lives.

---
 drivers/gpu/drm/drm_vblank.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -605,7 +605,8 @@ bool drm_calc_vbltimestamp_from_scanoutp
 	 */
 	if (mode->crtc_clock == 0) {
 		DRM_DEBUG("crtc %u: Noop due to uninitialized mode.\n", pipe);
-		WARN_ON_ONCE(drm_drv_uses_atomic_modeset(dev));
+		WARN_ONCE(drm_drv_uses_atomic_modeset(dev), "%s: report me.\n",
+			  dev->driver->name);
 
 		return false;
 	}