---
name: "drm_calc_timestamping_constants"
section: "9"
platform: "linux"
package: "linux-manual-3.16"
version: "3.16.56-1+deb8u1"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/drm_calc_timestamping_constants"
---

# drm\_calc\_timestamping\_constants(9)

calculate vblank timestamp constants

## NAME

drm\_calc\_timestamping\_constants - calculate vblank timestamp constants

## SYNOPSIS

**void drm\_calc\_timestamping\_constants(struct drm\_crtc \*** *crtc***, const struct drm\_display\_mode \*** *mode***);**

## ARGUMENTS

*crtc*

drm\_crtc whose timestamp constants should be updated.

*mode*

display mode containing the scanout timings

## DESCRIPTION

Calculate and store various constants which are later needed by vblank and swap-completion timestamping, e.g, by **drm\_calc\_vbltimestamp\_from\_scanoutpos**. They are derived from CRTC's true scanout timing, so they take things like panel scaling or other adjustments into account.

## AUTHORS

**Jesse Barnes** \<jesse.barnes@intel.com\>\
 Intel Corporation,

Initial version

**Laurent Pinchart** \<laurent.pinchart@ideasonboard.com\>\
 Ideas on board SPRL,

Driver internals

**Daniel Vetter** \<daniel.vetter@ffwll.ch\>\
 Intel Corporation,

Contributions all over the place

## COPYRIGHT