From: Sam Ravnborg <sam@ravnborg.org>
To: dri-devel@lists.freedesktop.org, Lyude Paul <lyude@redhat.com>
Cc: Neil Armstrong <narmstrong@baylibre.com>,
David Airlie <airlied@linux.ie>,
Liviu Dudau <liviu.dudau@arm.com>,
Andrzej Hajda <a.hajda@samsung.com>,
Nirmoy Das <nirmoy.das@amd.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Mihail Atanassov <Mihail.Atanassov@arm.com>,
Sam Ravnborg <sam@ravnborg.org>,
Emil Velikov <emil.velikov@collabora.com>,
David Francis <David.Francis@amd.com>,
James Qian Wang <james.qian.wang@arm.com>,
Jonas Karlman <jonas@kwiboo.se>,
Mikita Lipski <mikita.lipski@amd.com>,
Jernej Skrabec <jernej.skrabec@siol.net>,
Andrzej Pietrasiewicz <andrzej.p@collabora.com>,
Boris Brezillon <boris.brezillon@collabora.com>,
Thomas Zimmermann <tzimmermann@suse.de>,
Alex Deucher <alexander.deucher@amd.com>
Subject: [PATCH v1 1/6] drm/vblank: Add intro to documentation
Date: Sat, 28 Mar 2020 14:20:20 +0100 [thread overview]
Message-ID: <20200328132025.19910-2-sam@ravnborg.org> (raw)
In-Reply-To: <20200328132025.19910-1-sam@ravnborg.org>
Lyude Paul wrote a very good intro to vblank here:
https://lore.kernel.org/dri-devel/faf63d8a9ed23c16af69762f59d0dca6b2bf085f.camel@redhat.com/T/#mce6480be738160e9d07c5d023e88fd78d7a06d27
Add this to the intro chapter in drm_vblank.c so others
can benefit from it too.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Co-developed-by: Lyude Paul <lyude@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@linux.ie>
---
drivers/gpu/drm/drm_vblank.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
index bcf346b3e486..95cac22d59d1 100644
--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -41,6 +41,21 @@
/**
* DOC: vblank handling
*
+ * From the perspective of a computer, every time a computer monitor displays
+ * a new frame it's done by "scanning out" the display image from top to
+ * bottom, one row of pixels at a time. which row of pixels we're on is
+ * referred to as the scanline.
+ * Additionally, there's usually a couple of extra scanlines which we
+ * scan out, but aren't actually displayed on the screen (these sometimes
+ * get used by HDMI audio and friends, but that's another story).
+ * The period where we're on these scanlines is referred to as the vblank.
+ *
+ * On a lot of display hardware, programming needs to take effect during the
+ * vertical blanking period so that settings like gamma, what frame we're
+ * scanning out, etc. can be safely changed without showing visual tearing
+ * on the screen. In some unforgiving hardware, some of this programming has
+ * to both start and end in the same vblank - vertical blanking.
+ *
* Vertical blanking plays a major role in graphics rendering. To achieve
* tear-free display, users must synchronize page flips and/or rendering to
* vertical blanking. The DRM API offers ioctls to perform page flips
--
2.20.1
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next prev parent reply other threads:[~2020-03-28 13:20 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-28 13:20 [PATCH v1 0/6] drm: kernel-doc stuff Sam Ravnborg
2020-03-28 13:20 ` Sam Ravnborg [this message]
2020-03-30 11:29 ` [PATCH v1 1/6] drm/vblank: Add intro to documentation Thomas Zimmermann
2020-03-30 18:56 ` Sam Ravnborg
2020-03-30 18:57 ` [PATCH v2 " Sam Ravnborg
2020-03-30 21:51 ` Lyude Paul
2020-03-31 6:14 ` Thomas Zimmermann
2020-03-31 7:55 ` Daniel Vetter
2020-03-28 13:20 ` [PATCH v1 2/6] drm/fb: fix kernel-doc in drm_framebuffer.h Sam Ravnborg
2020-03-30 11:35 ` Andrzej Pietrasiewicz
2020-03-30 19:02 ` Sam Ravnborg
2020-03-28 13:20 ` [PATCH v1 3/6] drm/sched: fix kernel-doc in gpu_scheduler.h Sam Ravnborg
2020-03-31 7:54 ` Daniel Vetter
2020-04-05 20:38 ` Sam Ravnborg
2020-03-28 13:20 ` [PATCH v1 4/6] drm: writeback: document callbacks Sam Ravnborg
2020-03-31 7:53 ` Daniel Vetter
2020-04-05 22:56 ` Laurent Pinchart
2020-03-28 13:20 ` [PATCH v1 5/6] drm/dp_mst: add kernel-doc for drm_dp_mst_port.fec_capable Sam Ravnborg
2020-03-30 15:01 ` Lyude Paul
2020-03-30 19:05 ` Sam Ravnborg
2020-03-28 13:20 ` [PATCH v1 6/6] drm/bridge: fix kernel-doc warning in panel.c Sam Ravnborg
2020-03-31 7:48 ` Daniel Vetter
2020-04-05 20:37 ` Sam Ravnborg
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