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>,
Nicolas Ferre <nicolas.ferre@microchip.com>
Subject: Re: [PATCH 4/4] drm/atmel-hlcdc: do not immediately disable planes, wait for next frame
Date: Thu, 10 Jan 2019 20:25:22 +0100 [thread overview]
Message-ID: <20190110202522.10206f2d@bbrezillon> (raw)
In-Reply-To: <a31e6514-1643-9e47-cbb4-3323183fd370@axentia.se>
On Thu, 10 Jan 2019 18:51:21 +0000
Peter Rosin <peda@axentia.se> wrote:
> On 2019-01-10 18:29, Boris Brezillon wrote:
> > On Thu, 10 Jan 2019 15:10:48 +0000
> > Peter Rosin <peda@axentia.se> wrote:
> >
> >> The A2Q and UPDATE bits have no effect in the channel disable registers.
> >> However, since they are present, assume that the intention is to disable
> >> planes, not immediately as indicated by the RST bit, but on the next
> >> frame shift since that is what A2Q and UPDATE means in the channel enable
> >> registers.
> >>
> >> Disabling the plane on the next frame shift is done with the EN bit,
> >> so use that.
> >
> > It's been a long time, but I think I had a good reason for forcing a
> > reset. IIRC, when you don't do that and the CRTC is disabled before the
> > plane, the EN bit stays around, and next time you queue a plane update,
> > you'll start with an invalid buf pointer.
>
> It might be possible to clear the EN bit in ...CHDR before enabling the
> plane in ...CHER. Or is that too late?
I think I tried that, but I'm not sure (BTW, this change was done in
bd4248bb5e8b ("drm: atmel-hlcdc: reset layer A2Q and UPDATE bits when
disabling it")). Anyway, I'm not even sure this is still needed now
that atomic updates have a wait_for_flip_done/vblank() in the commit
path.
> But this patch is not overly
> important, I just wanted to avoid the resulting "black hole" when the
> plane DMA is disabled mid-frame. But disabling planes is probably not
> something that happens frequently and will perhaps not be noticed at
> all...
Okay. Other patches look good to me, I'm just waiting for Nicolas
feedback before applying them.
next prev parent reply other threads:[~2019-01-10 19:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-10 15:10 [PATCH 0/4] drm/atmel-hlcdc: fix plane clipping/rotation issues Peter Rosin
2019-01-10 15:10 ` [PATCH 1/4] drm/atmel-hlcdc: rotate planes counterclockwise Peter Rosin
2019-01-10 15:10 ` [PATCH 2/4] drm/atmel-hlcdc: do not swap w/h of the crtc when a plane is rotated Peter Rosin
2019-01-10 17:48 ` Boris Brezillon
2019-01-11 13:29 ` Peter Rosin
2019-01-11 14:14 ` Nicolas.Ferre
2019-01-10 15:10 ` [PATCH 3/4] drm/atmel-hlcdc: fix clipping of planes Peter Rosin
2019-01-10 15:10 ` [PATCH 4/4] drm/atmel-hlcdc: do not immediately disable planes, wait for next frame Peter Rosin
2019-01-10 17:29 ` Boris Brezillon
2019-01-10 18:51 ` Peter Rosin
2019-01-10 19:25 ` Boris Brezillon [this message]
2019-01-11 14:29 ` Peter Rosin
2019-01-16 14:45 ` Boris Brezillon
2019-01-10 17:45 ` [PATCH 0/4] drm/atmel-hlcdc: fix plane clipping/rotation issues Boris Brezillon
2019-01-10 20:16 ` Sam Ravnborg
2019-01-11 9:16 ` Peter Rosin
2019-01-10 21:24 ` Peter Rosin
2019-01-11 14:18 ` Nicolas.Ferre
2019-01-27 8:27 ` Boris Brezillon
2019-01-31 13:13 ` Peter Rosin
2019-01-31 13:21 ` Boris Brezillon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190110202522.10206f2d@bbrezillon \
--to=bbrezillon@kernel.org \
--cc=airlied@linux.ie \
--cc=alexandre.belloni@bootlin.com \
--cc=boris.brezillon@bootlin.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=nicolas.ferre@microchip.com \
--cc=peda@axentia.se \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).