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From: "Ville Syrjälä" <ville.syrjala-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: "Noralf Trønnes" <noralf-L59+Z2yzLopAfugRpC6u6w@public.gmane.org>
Cc: "Boris Brezillon"
	<boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>,
	"Thomas Hellstrom"
	<thellstrom-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>,
	amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	"David Airlie" <airlied-cv59FeDIM0c@public.gmane.org>,
	"Daniel Vetter" <daniel.vetter-/w4YWyX8dFk@public.gmane.org>,
	intel-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	"Seung-Woo Kim"
	<sw0312.kim-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	"Kyungmin Park"
	<kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>,
	"VMware Graphics"
	<linux-graphics-maintainer-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org>,
	"Gerd Hoffmann" <kraxel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-arm-msm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	"Alex Deucher" <alexander.deucher-5C7GfCeVMHo@public.gmane.org>,
	"Shawn Guo" <shawnguo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	freedreno-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	"Vincent Abriou" <vincent.abriou-qxv4g6HH51o@public.gmane.org>,
	"Christian König" <christian.koenig-5C7GfCeVMHo@public.gmane.org>
Subject: Re: [PATCH 00/23] drm: Eliminate plane->fb/crtc usage for atomic drivers
Date: Thu, 22 Mar 2018 20:49:12 +0200	[thread overview]
Message-ID: <20180322184912.GM5453@intel.com> (raw)
In-Reply-To: <b92fe986-295c-fecb-dca1-82cb9bf7b7b1-L59+Z2yzLopAfugRpC6u6w@public.gmane.org>

On Thu, Mar 22, 2018 at 05:51:35PM +0100, Noralf Trønnes wrote:
> tinydrm is also using plane->fb:
> 
> $ grep -r "plane\.fb" drivers/gpu/drm/tinydrm/
> drivers/gpu/drm/tinydrm/repaper.c:      if (tdev->pipe.plane.fb != fb)
> drivers/gpu/drm/tinydrm/mipi-dbi.c:     if (tdev->pipe.plane.fb != fb)
> drivers/gpu/drm/tinydrm/mipi-dbi.c:     struct drm_framebuffer *fb = 
> mipi->tinydrm.pipe.plane.fb;

Oh dear, and naturally it's the most annoying one of the bunch. So we
want to take the plane lock in the fb.dirty() hook to look at the fb,
but mipi-dbi.c calls that directly from the bowels of its
.atomic_enable() hook. So that would deadlock pretty neatly if the
commit happens while already holding the lock.

So we'd either need to plumb an acquire context into fb.dirty(),
or maybe have tinydrm provide a lower level lockless dirty() hook
that gets called by both (there are just too many layers in this
particular cake to immediately see where such a hook would be best
placed). Or maybe there's some other solution I didn't think of.

Looking at this I'm also left wondering how this is supposed
handle fb.dirty() getting called concurrently with a modeset.
The dirty_mutex only seems to offer any protection for
fb.dirty() against another fb.dirty()...

-- 
Ville Syrjälä
Intel OTC
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  parent reply	other threads:[~2018-03-22 18:49 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-22 15:22 [PATCH 00/23] drm: Eliminate plane->fb/crtc usage for atomic drivers Ville Syrjala
2018-03-22 15:22 ` [PATCH 01/23] Revert "drm/atomic-helper: Fix leak in disable_all" Ville Syrjala
2018-03-22 15:22 ` [PATCH 02/23] drm/atomic-helper: Make drm_atomic_helper_disable_all() update the plane->fb pointers Ville Syrjala
2018-03-26 20:28   ` Daniel Vetter
2018-03-29 16:32     ` Ville Syrjälä
2018-03-26 20:43   ` Daniel Vetter
2018-03-22 15:22 ` [PATCH 03/23] drm: Clear crtc->primary->crtc when disabling the crtc via setcrtc() Ville Syrjala
2018-03-26 20:41   ` Daniel Vetter
2018-03-22 15:22 ` [PATCH 04/23] drm/atomic-helper: WARN if legacy plane fb pointers are bogus when committing duplicated state Ville Syrjala
2018-03-26 20:42   ` [Intel-gfx] " Daniel Vetter
2018-03-22 15:22 ` [PATCH 05/23] drm: Add local 'plane' variable for primary/cursor planes Ville Syrjala
2018-03-26 20:49   ` Daniel Vetter
2018-03-22 15:22 ` [PATCH 06/23] drm: Adjust whitespace for legibility Ville Syrjala
2018-03-26 20:49   ` Daniel Vetter
2018-03-22 15:22 ` [PATCH 07/23] drm: Make the fb refcount handover less magic Ville Syrjala
2018-03-27  7:49   ` Daniel Vetter
2018-03-22 15:22 ` [PATCH 08/23] drm: Use plane->state->fb over plane->fb Ville Syrjala
2018-03-27  8:10   ` Daniel Vetter
2018-03-22 15:22 ` [PATCH 09/23] drm/i915: Stop consulting plane->fb Ville Syrjala
2018-03-22 15:23 ` [PATCH 11/23] drm/sti: " Ville Syrjala
2018-03-22 16:25   ` Benjamin Gaignard
2018-03-22 15:23 ` [PATCH 12/23] drm/vmwgfx: " Ville Syrjala
2018-03-22 15:53   ` Thomas Hellstrom
2018-03-22 15:23 ` [PATCH 13/23] drm/zte: " Ville Syrjala
2018-03-22 16:12   ` Maarten Lankhorst
2018-03-22 17:40   ` [PATCH v2 " Ville Syrjala
2018-03-26  7:25     ` Shawn Guo
2018-03-26 12:14   ` [PATCH v3 13/23] drm/zte: Stop consulting plane->crtc Ville Syrjala
2018-03-22 15:23 ` [PATCH 14/23] drm/atmel-hlcdc: Stop using plane->fb Ville Syrjala
2018-03-22 16:14   ` Maarten Lankhorst
2018-03-22 17:30     ` Ville Syrjälä
2018-03-27  8:13   ` Daniel Vetter
2018-03-22 15:23 ` [PATCH 15/23] drm: Stop updating plane->crtc/fb/old_fb on atomic drivers Ville Syrjala
2018-03-26 20:52   ` Daniel Vetter
2018-03-26 20:56     ` [Intel-gfx] " Daniel Vetter
2018-03-27  7:57   ` Daniel Vetter
2018-03-27  9:44     ` [Intel-gfx] " Ville Syrjälä
2018-03-22 15:23 ` [PATCH 16/23] drm/amdgpu/dc: Stop updating plane->fb Ville Syrjala
2018-03-23 20:23   ` Harry Wentland
2018-03-22 15:23 ` [PATCH 17/23] drm/i915: Stop updating plane->fb/crtc Ville Syrjala
2018-03-22 15:23 ` [PATCH 18/23] drm/exynos: Stop updating plane->crtc Ville Syrjala
     [not found] ` <20180322152313.6561-1-ville.syrjala-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-03-22 15:23   ` [PATCH 10/23] drm/msm: Stop consulting plane->fb Ville Syrjala
2018-03-22 15:23   ` [PATCH 19/23] drm/msm: Stop updating plane->fb/crtc Ville Syrjala
2018-03-27  8:21   ` [PATCH 00/23] drm: Eliminate plane->fb/crtc usage for atomic drivers Daniel Vetter
2018-03-22 15:23 ` [PATCH 20/23] drm/virtio: Stop updating plane->fb Ville Syrjala
2018-03-22 16:11   ` Gerd Hoffmann
2018-03-22 17:40   ` [PATCH v2 20/23] drm/virtio: Stop updating plane->crtc Ville Syrjala
2018-03-22 15:23 ` [PATCH 21/23] drm/vc4: Stop updating plane->fb/crtc Ville Syrjala
2018-03-22 16:50   ` Maarten Lankhorst
2018-03-22 15:23 ` [PATCH 22/23] drm/i915: Restore planes after load detection Ville Syrjala
2018-03-22 15:23 ` [PATCH 23/23] drm/i915: Make force_load_detect effective even w/ DMI quirks/hotplug Ville Syrjala
2018-03-22 16:49   ` Maarten Lankhorst
2018-03-22 17:41   ` [PATCH v2 " Ville Syrjala
2018-03-22 16:38 ` ✗ Fi.CI.CHECKPATCH: warning for drm: Eliminate plane->fb/crtc usage for atomic drivers Patchwork
2018-03-22 16:51 ` [PATCH 00/23] " Noralf Trønnes
     [not found]   ` <b92fe986-295c-fecb-dca1-82cb9bf7b7b1-L59+Z2yzLopAfugRpC6u6w@public.gmane.org>
2018-03-22 18:49     ` Ville Syrjälä [this message]
2018-03-22 23:28       ` Noralf Trønnes
2018-03-22 16:52 ` ✗ Fi.CI.BAT: failure for " Patchwork
2018-03-22 17:54 ` [PATCH 00/23] " Emil Velikov
     [not found]   ` <CACvgo53B4zLLUqw9y18skpjacmjt-iAYBcG19HkmE=jFwcb4+w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2018-03-22 18:03     ` Harry Wentland
     [not found]       ` <a0d3ec32-be68-c96e-607c-0af4a97a3dd6-5C7GfCeVMHo@public.gmane.org>
2018-03-22 18:34         ` Emil Velikov
2018-03-22 17:56 ` ✗ Fi.CI.CHECKPATCH: warning for drm: Eliminate plane->fb/crtc usage for atomic drivers (rev4) Patchwork
2018-03-22 18:12 ` ✓ Fi.CI.BAT: success " Patchwork
2018-03-22 19:59 ` ✗ Fi.CI.IGT: failure " Patchwork
2018-03-26 12:28 ` ✗ Fi.CI.CHECKPATCH: warning for drm: Eliminate plane->fb/crtc usage for atomic drivers (rev5) Patchwork
2018-03-26 12:43 ` ✓ Fi.CI.BAT: success " Patchwork
2018-03-26 15:36 ` ✓ Fi.CI.IGT: " Patchwork

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