You're right. DC5 could disrupt GMBUS. We forgot to add a note on GMBUS when it got moved under DMC domain in GLK and BXT/APL. I'll take care of that. -----Original Message----- From: Ville Syrjälä [mailto:ville.syrjala@xxxxxxxxxxxxxxx] Sent: Monday, 11 December, 2017 11:03 AM To: Pandiyan, Dhinakaran <dhinakaran.pandiyan@xxxxxxxxx> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; Runyan, Arthur J <arthur.j.runyan@xxxxxxxxx> Subject: Re: [PATCH 1/4] drm/i915: Disable DC states around GMBUS on GLK On Mon, Dec 11, 2017 at 06:41:05PM +0000, Pandiyan, Dhinakaran wrote: > On Fri, 2017-12-08 at 23:37 +0200, Ville Syrjala wrote: > > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > > > Prevent the DMC from destroying GMBUS transfers on GLK. GMBUS > > lives in PG1 so DC off is all we need. > > > Just so that I understand this correctly. DMC is expected to take care > of managing power for GMBUS transfers without the driver explicitly > turning on/off the power well 1 but it isn't. Do you know if this is a > DMC regression? No idea. The docs don't seem to even mention DMC and GMBUS in the same sentence. But since DP AUX needs DC off I don't see why GMBUS would be all that different. And with bit banging I would be somewhat surprised if DMC could maintain the state of the pins while in DC5. Although I suppose it might be possible that the hw automagically prevents DC5 when we're driving any of the pins. Art? > > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > > --- > > drivers/gpu/drm/i915/intel_runtime_pm.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c > > index 96ab74f3d101..522e0a63090f 100644 > > --- a/drivers/gpu/drm/i915/intel_runtime_pm.c > > +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c > > @@ -1792,6 +1792,7 @@ void intel_display_power_put(struct drm_i915_private *dev_priv, > > BIT_ULL(POWER_DOMAIN_GT_IRQ) | \ > > BIT_ULL(POWER_DOMAIN_MODESET) | \ > > BIT_ULL(POWER_DOMAIN_AUX_A) | \ > > + BIT_ULL(POWER_DOMAIN_GMBUS) | \ > > BIT_ULL(POWER_DOMAIN_INIT)) > > > > #define CNL_DISPLAY_POWERWELL_2_POWER_DOMAINS ( \ -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
