From: Boris Brezillon <bbrezillon@kernel.org>
To: Peter Rosin <peda@axentia.se>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>,
David Airlie <airlied@linux.ie>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Boris Brezillon <boris.brezillon@bootlin.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] drm/atmel-hlcdc: prevent divide by zero
Date: Wed, 9 Jan 2019 13:00:08 +0100 [thread overview]
Message-ID: <20190109125833.0af5dc52@bbrezillon> (raw)
In-Reply-To: <9b73f5fa-e5c2-ea55-8d96-be6de8a1f34a@axentia.se>
On Wed, 9 Jan 2019 11:37:19 +0000
Peter Rosin <peda@axentia.se> wrote:
> On 2019-01-09 11:12, Daniel Vetter wrote:
> > On Tue, Jan 08, 2019 at 12:31:36PM +0000, Peter Rosin wrote:
> >> While trying to temporarily hide a plane, one thing that was attempted
> >> was to call (from libdrm)
> >>
> >> drmModeSetPlane(fd, plane_id, crtc_id, fb_id, 0,
> >> 0, 0, 0, 0, 0, 0, 0, 0);
> >>
> >> This call causes a pair of "Division by zero in kernel." messages. Kill
> >> those messages, but preserve the current behaviour that also happen to
> >> make the plane disappear with the above call.
> >>
> >> Signed-off-by: Peter Rosin <peda@axentia.se>
> >> ---
> >> drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 14 ++++++++++----
> >> 1 file changed, 10 insertions(+), 4 deletions(-)
> >>
> >> Side note, when comparing with drm_atomic_helper_check_plane_state(), I get
> >> the feeling that the src rect should be clipped together with the crtc rect
> >> if/when clipping is needed. That function calls drm_rect_clip_scaled(), and
> >> the equivalent does not seem to happen here. Should clipping be performed
> >> on the src rect?
> >
> > Any reasons atmel can't switch over to that helper? Would compute a nice
> > ->visible state variable for you ...
> > -Daniel
>
> I have not researched that, and as stated above, I was not sure if that was the
> correct approach to begin with. Boris, any insights?
You can look at vc4_plane.c if you want an example of how this helper
can be used to get clipped dimensions of the plane.
> Does this code predate the
> helper or something?
Yes, and I must admit I'm not actively maintaining the driver, so there
are probably a few other things we could simplify by using generic
helpers.
>
> Maybe there's some register bit that hides a plane explicitly, matching the
> ->visible state variable? I haven't looked at that either...
I don't think so, but you can simply disable the plane when ->visible
is false.
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WARNING: multiple messages have this Message-ID (diff)
From: Boris Brezillon <bbrezillon@kernel.org>
To: Peter Rosin <peda@axentia.se>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
David Airlie <airlied@linux.ie>,
Nicolas Ferre <nicolas.ferre@microchip.com>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
Boris Brezillon <boris.brezillon@bootlin.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] drm/atmel-hlcdc: prevent divide by zero
Date: Wed, 9 Jan 2019 13:00:08 +0100 [thread overview]
Message-ID: <20190109125833.0af5dc52@bbrezillon> (raw)
In-Reply-To: <9b73f5fa-e5c2-ea55-8d96-be6de8a1f34a@axentia.se>
On Wed, 9 Jan 2019 11:37:19 +0000
Peter Rosin <peda@axentia.se> wrote:
> On 2019-01-09 11:12, Daniel Vetter wrote:
> > On Tue, Jan 08, 2019 at 12:31:36PM +0000, Peter Rosin wrote:
> >> While trying to temporarily hide a plane, one thing that was attempted
> >> was to call (from libdrm)
> >>
> >> drmModeSetPlane(fd, plane_id, crtc_id, fb_id, 0,
> >> 0, 0, 0, 0, 0, 0, 0, 0);
> >>
> >> This call causes a pair of "Division by zero in kernel." messages. Kill
> >> those messages, but preserve the current behaviour that also happen to
> >> make the plane disappear with the above call.
> >>
> >> Signed-off-by: Peter Rosin <peda@axentia.se>
> >> ---
> >> drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c | 14 ++++++++++----
> >> 1 file changed, 10 insertions(+), 4 deletions(-)
> >>
> >> Side note, when comparing with drm_atomic_helper_check_plane_state(), I get
> >> the feeling that the src rect should be clipped together with the crtc rect
> >> if/when clipping is needed. That function calls drm_rect_clip_scaled(), and
> >> the equivalent does not seem to happen here. Should clipping be performed
> >> on the src rect?
> >
> > Any reasons atmel can't switch over to that helper? Would compute a nice
> > ->visible state variable for you ...
> > -Daniel
>
> I have not researched that, and as stated above, I was not sure if that was the
> correct approach to begin with. Boris, any insights?
You can look at vc4_plane.c if you want an example of how this helper
can be used to get clipped dimensions of the plane.
> Does this code predate the
> helper or something?
Yes, and I must admit I'm not actively maintaining the driver, so there
are probably a few other things we could simplify by using generic
helpers.
>
> Maybe there's some register bit that hides a plane explicitly, matching the
> ->visible state variable? I haven't looked at that either...
I don't think so, but you can simply disable the plane when ->visible
is false.
next prev parent reply other threads:[~2019-01-09 12:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-08 12:31 [PATCH] drm/atmel-hlcdc: prevent divide by zero Peter Rosin
2019-01-08 12:31 ` Peter Rosin
2019-01-09 10:12 ` Daniel Vetter
2019-01-09 10:12 ` Daniel Vetter
2019-01-09 10:12 ` Daniel Vetter
2019-01-09 11:37 ` Peter Rosin
2019-01-09 11:37 ` Peter Rosin
2019-01-09 12:00 ` Boris Brezillon [this message]
2019-01-09 12:00 ` Boris Brezillon
2019-01-09 11:37 ` Boris Brezillon
2019-01-09 11:37 ` Boris Brezillon
2019-01-09 11:37 ` Boris Brezillon
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