drm/i915: Keep min freq above floor on HSW/BDW

Set the min_freq_softlimit to max(RPe, 450MHz).

Setting a floor can ensure a minimum experience
level.  The 450MHz value came from a power and
performance study of various types of workloads
(3D, Media, GPGPU, idle, etc).

v2: rebased

Signed-off-by: Tom O'Rourke <Tom.O'Rourke@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index eb2a0a85e057eacd5f2eaf064a534007fa294c02..6d0795d3b2e4a97690e822672911cf0dd44ee0e6 100644 (file)
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4643,7 +4643,8 @@ static void gen6_init_rps_frequencies(struct drm_device *dev)
        if (dev_priv->rps.min_freq_softlimit == 0) {
                if (IS_HASWELL(dev) || IS_BROADWELL(dev))
                        dev_priv->rps.min_freq_softlimit =
-                               dev_priv->rps.efficient_freq;
+                               /* max(RPe, 450 MHz) */
+                               max(dev_priv->rps.efficient_freq, (u8) 9);
                else
                        dev_priv->rps.min_freq_softlimit =
                                dev_priv->rps.min_freq;