Round to nearest floating point rounding mode

1

Hi PowerVR team,

I have a question about floating point rounding modes on your GPUs.
I can see that currently no PowerVR GPU on the market that support round to nearest even mode. Even latest GPU, GM9446, has only round to zero. I understand that round to zero maybe easier to implement(cheaper) in hardware. And also that this mode is good enough for graphics. But compute is more and more popular on mobile GPUs and in this case RTN more preferable and desired over RTZ mode.
All major mobile GPU vendors support RTN mode, Mali(at least from T series), Adreno(from 4xx series), Apple(from A11 Bionic), but not PowerVR.
And the question is are you going to support it? Will you add it in IMG-A/B/C?
RTN is required for support of OpenCL 2.0 Full profile, but on your site I can see that IMG-A will support only embedded profile.

Thanks, Roman

2

Hi Roserg,

The A-Series architecture only supports RTZ again but having multiple rounding modes (including RTN) is a proposed feature for B series onward. However your request has been noted and hopefully we will see other rounding modes in the future.

Thanks,
David

3

Hi,
Can I get updated information about supported rounding modes for IMG-B/C/D?

Thanks,
Raman Sarokin

4

Hi, Raman.

All our new cores: Series B, C and D have RTE rounding mode. Only one variant (BXM-8-256) has RTZ.

Best regards.

Carlos.