[Intel-gfx] TIMESTAMP register

Daniel Vetter daniel at ffwll.ch
Tue Apr 17 21:39:43 CEST 2012

On Tue, Apr 17, 2012 at 07:12:40PM +0000, Lawrynowicz, Jacek wrote:
> Starting from IVB the main TIMESTAMP register is longer than 32 bits
> (it’s 36 bits long).
> How should we pass its 36 bit value from i915 to user space?
> GET_PARAM ioctls supports only 32 bit params. Should we add GET_PARAM64
> or create separate ioctl to access the TIMESTAMP?
> Any suggestions?
> This functionality is required for any OpenGL driver which implements GL_ARB_timer_query.

Like occlusion queries I presume this should be done with a pipe control
qword write issued from a batch. GETPARAM makes absolutely no sense, that
is for driver features, not hw features and just used so that a new driver
also can work on an older kernel.
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48

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