[PATCH] drm/i915: make default minimum frequency RP1 instead of RPN

[PATCH] drm/i915: make default minimum frequency RP1 instead of RPN

[Jesse Barnes]

We should only ever go below RP1 for thermal reasons.  Users can still
control this through sysfs by manually reducing the minimum frequency
(and max if they want to clamp their frequency for power reasons, e.g.
to keep fans off or something).

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
---
 drivers/gpu/drm/i915/intel_pm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 59068be..2c2701e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2432,7 +2432,7 @@ static void gen6_enable_rps(struct drm_device *dev)
 
 	/* In units of 100MHz */
 	dev_priv->rps.max_delay = rp_state_cap & 0xff;
-	dev_priv->rps.min_delay = (rp_state_cap & 0xff0000) >> 16;
+	dev_priv->rps.min_delay = (rp_state_cap & 0xff00) >> 8;
 	dev_priv->rps.cur_delay = 0;
 
 	/* disable the counters and set deterministic thresholds */
-- 
1.7.9.5

Re: [PATCH] drm/i915: make default minimum frequency RP1 instead of RPN

[Eric Anholt]

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Jesse Barnes <jbarnes@virtuousgeek.org> writes:

> We should only ever go below RP1 for thermal reasons.  Users can still
> control this through sysfs by manually reducing the minimum frequency
> (and max if they want to clamp their frequency for power reasons, e.g.
> to keep fans off or something).

I think I know what the reasoning is, but this commit message could use
some justification on why you wouldn't want to use the lowest frequency
available.

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Re: [PATCH] drm/i915: make default minimum frequency RP1 instead of RPN

[Jesse Barnes]

On Fri, 26 Oct 2012 11:32:08 -0700
Eric Anholt <eric@anholt.net> wrote:

> Jesse Barnes <jbarnes@virtuousgeek.org> writes:
> 
> > We should only ever go below RP1 for thermal reasons.  Users can still
> > control this through sysfs by manually reducing the minimum frequency
> > (and max if they want to clamp their frequency for power reasons, e.g.
> > to keep fans off or something).
> 
> I think I know what the reasoning is, but this commit message could use
> some justification on why you wouldn't want to use the lowest frequency
> available.

Yeah I should have been more verbose.

RP1 is the lowest "normal" frequency, in that it's the highest we can
run at the base voltage level for the part.  This means that any lower
frequencies will simply make things take longer and not make up for it
in power savings because the voltage is already at the minimum.

Daniel, feel free to add the above to the changelog if you want.

-- 
Jesse Barnes, Intel Open Source Technology Center