From: Thomas Zimmermann <tzimmermann@suse.de>
To: Emil Velikov <emil.l.velikov@gmail.com>
Cc: david@lechnology.com, oleksandr_andrushchenko@epam.com,
"Dave Airlie" <airlied@linux.ie>,
"Sam Ravnborg" <sam@ravnborg.org>,
"ML dri-devel" <dri-devel@lists.freedesktop.org>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"open list:VIRTIO GPU DRIVER"
<virtualization@lists.linux-foundation.org>,
"Hans de Goede" <hdegoede@redhat.com>,
"Noralf Trønnes" <noralf@tronnes.org>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Daniel Vetter" <daniel@ffwll.ch>,
xen-devel@lists.xenproject.org,
"Emil Velikov" <emil.velikov@collabora.com>,
"Sean Paul" <sean@poorly.run>,
"Laurent Pinchart" <laurent.pinchart@ideasonboard.com>
Subject: Re: [Xen-devel] [PATCH v4 01/15] drm: Initialize struct drm_crtc_state.no_vblank from device settings
Date: Mon, 27 Jan 2020 19:42:27 +0100 [thread overview]
Message-ID: <183782e6-164c-bae8-90e0-906edb059a1d@suse.de> (raw)
In-Reply-To: <CACvgo53YvKjPNNshZoTjJehHyOX6e05kJ5gAXtjwxs+oLLv7vw@mail.gmail.com>
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Hi Emil
Am 27.01.20 um 19:12 schrieb Emil Velikov:
> Hi Thomas,
>
> On Thu, 23 Jan 2020 at 09:21, Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
>> @@ -174,12 +174,22 @@ struct drm_crtc_state {
>> * @no_vblank:
>> *
>> * Reflects the ability of a CRTC to send VBLANK events. This state
>> - * usually depends on the pipeline configuration, and the main usuage
>> - * is CRTCs feeding a writeback connector operating in oneshot mode.
>> - * In this case the VBLANK event is only generated when a job is queued
>> - * to the writeback connector, and we want the core to fake VBLANK
>> - * events when this part of the pipeline hasn't changed but others had
>> - * or when the CRTC and connectors are being disabled.
>> + * usually depends on the pipeline configuration. If set to true, DRM
>> + * atomic helpers will sendout a fake VBLANK event during display
>> + * updates.
>> + *
>> + * One usage is for drivers and/or hardware without support for VBLANK
>> + * interrupts. Such drivers typically do not initialize vblanking
>> + * (i.e., call drm_vblank_init() wit the number of CRTCs). For CRTCs
>> + * without initialized vblanking, the field is initialized to true and
>> + * a VBLANK event will be send out on each update of the display
>> + * pipeline.
>> + *
>> + * Another usage is CRTCs feeding a writeback connector operating in
>> + * oneshot mode. In this case the VBLANK event is only generated when
>> + * a job is queued to the writeback connector, and we want the core
>> + * to fake VBLANK events when this part of the pipeline hasn't changed
>> + * but others had or when the CRTC and connectors are being disabled.
>> *
>
> Perhaps it's just me, yet the following ideas would make the topic
> significantly easier and clearer.
>
> - adding explicit "fake" when talking about drm/atomic _helpers_
> generating/sending a VBLANK event.
> For example, in 15/15 the commit message says "fake", while inline
> comment omits it... Leading to the confusion pointed out.
No problem on being more precise here. I'll update the docs accordingly.
>
> - s/no_vblank/fake_vblank/g or s/no_vblank/no_hw_vblank/g
> Simple and concise. With slight inclination towards the former wording :-)
I'd prefer to not change the field's name. The current name 'no_vblank'
indicates state and lets helpers decide what to do with it. The name
'fake_vblank' indicates an instruction to the helpers, telling them what
to do. It does neither seem to fit into drm_crtc_state, nor into the
overall concept.
Best regards
Thomas
>
> If you and Daniel agree with the rename, then the first sentence of
> the description should probably be tweaked.
>
> HTH
> Emil
>
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer
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next prev parent reply other threads:[~2020-01-27 18:42 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 9:21 [Xen-devel] [PATCH v4 00/15] Use no_vblank property for drivers without VBLANK Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 01/15] drm: Initialize struct drm_crtc_state.no_vblank from device settings Thomas Zimmermann
2020-01-27 9:40 ` Daniel Vetter
2020-01-27 18:12 ` Emil Velikov
2020-01-27 18:42 ` Thomas Zimmermann [this message]
2020-01-28 15:14 ` Daniel Vetter
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 02/15] drm/arc: Remove sending of vblank event Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 03/15] drm/ast: Don't set struct drm_crtc_state.no_vblank explictly Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 04/15] drm/bochs: Remove sending of vblank event Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 05/15] drm/cirrus: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 06/15] drm/gm12u320: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 07/15] drm/ili9225: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 08/15] drm/mipi-dbi: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 09/15] drm/qxl: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 10/15] drm/repaper: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 11/15] drm/st7586: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 12/15] drm/udl: Don't set struct drm_crtc_state.no_vblank explictly Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 13/15] drm/vboxvideo: Remove sending of vblank event Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 14/15] drm/virtio: " Thomas Zimmermann
2020-01-23 9:21 ` [Xen-devel] [PATCH v4 15/15] drm/xen: Explicitly disable automatic " Thomas Zimmermann
2020-01-27 9:47 ` Daniel Vetter
2020-01-27 9:53 ` Oleksandr Andrushchenko
2020-01-27 11:59 ` Thomas Zimmermann
2020-01-27 12:10 ` Oleksandr Andrushchenko
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