[Intel-gfx] [PATCH 5/7] drm/i915/skl: Updated the gen9_enable_rps function

[Akash Goel]

On Tue, 2015-02-17 at 15:47 +0000, Damien Lespiau wrote:
> On Fri, Feb 06, 2015 at 08:26:36PM +0530, akash.goel at intel.com wrote:
> > From: Akash Goel <akash.goel at intel.com>
> > 
> > On SKL, GT frequency is programmed in units of 16.66 MHZ units compared
> > to 50 MHZ for older platforms. Also the time value specified for Up/Down EI &
> > Up/Down thresholds are expressed in units of 1.33 us, compared to 1.28
> > us for older platforms. So updated the gen9_enable_rps function as per that.
> > 
> > Signed-off-by: Akash Goel <akash.goel at intel.com>
> 
> The function was following exactly what is in the PM programming guide,
> so it should be correct, not sure we want to change that. Your version
> looks more readable though. 
> 
> I think I'd rather keep the close to the PM guide, but others may
> disagree.

Actually I am not sure, whether some of the values provided in the
programming guide are correct or not.

As per the values programmed for EI intervals, it seemed that was done
with an assumption of 1.28 us unit.
Like	0x101d0 * 1.28 = 84.8 ms (Standard value of Up EI)
	0x55730 * 1.28 = 448 ms  (Standard value of Down EI)
	0xe808  * 1.28 = 76 ms (90% of Up EI)
	0x3bd08 * 1.28 = 313 ms (70% of Down EI)

Also the value 0xf4240 (1000000 or 1 second), used for
GEN6_RP_DOWN_TIMEOUT, wasn't converted appropriately to time units.


Best regards
Akash