Hi Thomas,
On Thu, 23 Jan 2020 at 09:21, Thomas Zimmermann <tzimmermann@xxxxxxx> 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.
- s/no_vblank/fake_vblank/g or s/no_vblank/no_hw_vblank/g
Simple and concise. With slight inclination towards the former wording :-)
If you and Daniel agree with the rename, then the first sentence of
the description should probably be tweaked.
HTH
Emil
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