On Thu, Jun 12, 2014 at 03:37:18PM +0800, Lee, Chon Ming wrote: > On 06/12 08:14, S, Deepak wrote: > > > > > > On 6/11/2014 10:26 PM, Ville Syrjälä wrote: > > >On Fri, Jun 06, 2014 at 08:03:20AM -0700, Jesse Barnes wrote: > > >>On Fri, 6 Jun 2014 11:29:24 +0300 > > >>Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote: > > >> > > >>>On Thu, Jun 05, 2014 at 01:49:34PM -0700, Jesse Barnes wrote: > > >>>>This may take awhile (~10ms), and we don't need to make noise about it. > > >>>> > > >>>>References: https://bugs.freedesktop.org/show_bug.cgi?id=75244 > > >>>>Tested-by: huax.lu@xxxxxxxxx > > >>>>Signed-off-by: Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> > > >>>>--- > > >>>> drivers/gpu/drm/i915/intel_pm.c | 4 ---- > > >>>> 1 file changed, 4 deletions(-) > > >>>> > > >>>>diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c > > >>>>index ee27d74..4eebfd8 100644 > > >>>>--- a/drivers/gpu/drm/i915/intel_pm.c > > >>>>+++ b/drivers/gpu/drm/i915/intel_pm.c > > >>>>@@ -3227,10 +3227,6 @@ static void vlv_set_rps_idle(struct drm_i915_private *dev_priv) > > >>>> vlv_punit_write(dev_priv, PUNIT_REG_GPU_FREQ_REQ, > > >>>> dev_priv->rps.min_freq_softlimit); > > >>>> > > >>>>- if (wait_for(((vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS)) > > >>>>- & GENFREQSTATUS) == 0, 5)) > > >>>>- DRM_ERROR("timed out waiting for Punit\n"); > > >>>>- > > >>> > > >>>As I recall the entire point of this was to make sure the frequency > > >>>really drops before we allow turning off the clock. I'm not sure if we > > >>>can trust that the frequency (and more importantly the voltage) will > > >>>drop if we allow turning off the clock before the transition is > > >>>complete. > > >> > > >>well, we may need to increase the timeout then... let's see if that > > >>helps with the bug. > > > > > >FYI I played around with my BYT a bit and it doesn't appear to require > > >this "force gfx clock on" part of the workaround. > > > > > >I was polling VLV_GTLC_SURVIVABILITY_REG and VLV_GTLC_PW_STATUS to make > > >sure both render and media wells and the gfx clock remain off, and I > > >was also monitoring vnn via svid. While that was going on I just rewrote > > >PUNIT_REG_GPU_FREQ_REQ to make Punit change the frequency, and sure > > >enough it did, and svid showed me that vnn had also changed. So it > > >appears there's no need to have the gfx clock on to change its frequency > > >on this BYT. > > > > > >I wonder if this part of the workaround was only needed on older parts. > > >Deepak, any ideas? > > > > Yes ville, this was added initial for older parts and force gfx > > clock was part of the workaround. > > We have not verified this on newer parts. Let me check with hw guys > > to see if workaround still exits and when this was fixed. > > > > Thanks > > Deepak > > This is a bit side topic. In the vlv_set_rps_idle, it try to mask the turbo > interrupt by writing to GEN6_PMINTRMSK (offset 0xA168). But based on the bspec, > the PMIMR for BYT/GEN6 should be 0x44024 (GEN6_PMIMR). > > Not sure I miss anything. If there offset is wrong, mean the turbo has not mask at > all. Afaik PM interrupt handling has 3 levels: GEN6_PMINTRMSK is the lowest and only provides a mask to prevent irq event forwarding, GEN6_PMI[IEMS]R are the normal set of 4 registers and then there's the PM interrupt bit in the DE interrupt registers. Iirc masking in PMINTRMSK has power benefits, but I'm not sure. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
