Re: [PATCH 14/15] drm/i915: vlv: add runtime PM support

[Imre Deak <imre.deak@intel.com>]

On Wed, 2014-04-09 at 13:40 -0300, Paulo Zanoni wrote:
> 2014-04-08 13:57 GMT-03:00 Imre Deak <imre.deak@intel.com>:
> > Add runtime PM support for VLV, but leave it disabled. The next patch
> > enables it.
> >
> > The suspend/resume sequence used is based on [1] and [2]. In practice we
> > depend on the GT RC6 mechanism to save the HW context depending on the
> > render and media power wells. By the time we run the runtime suspend
> > callback the display side is also off and the HW context for that is
> > managed by the display power domain framework.
> >
> > Besides the above there are Gunit registers that depend on a system-wide
> > power well. This power well goes off once the device enters any of the
> > S0i[R123] states. To handle this scenario, save/restore these Gunit
> > registers. Note that this is not the complete register set dictated by
> > [2], to remove some overhead registers that are known not to be used are
> > ignored. Also some registers are fully setup by initialization functions
> > called during resume, these are not saved either. The list of registers
> > can be further reduced, see the TODO note in the code.
> >
> > [1] VLV_gfx_clocking_PM_reset_y12w21d3 / "Driver D3 entry/exit"
> > [2] VLV2_S0IXRegs
> >
> > Signed-off-by: Imre Deak <imre.deak@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c | 170 +++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 166 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > index 9f9d0db..16ca37f 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -891,19 +891,23 @@ static int i915_pm_poweroff(struct device *dev)
> >         return i915_drm_freeze(drm_dev);
> >  }
> >
> > -static void snb_runtime_suspend(struct drm_i915_private *dev_priv)
> > +static int snb_runtime_suspend(struct drm_i915_private *dev_priv)
> >  {
> >         struct drm_device *dev = dev_priv->dev;
> >
> >         intel_runtime_pm_disable_interrupts(dev);
> > +
> > +       return 0;
> >  }
> >
> > -static void hsw_runtime_suspend(struct drm_i915_private *dev_priv)
> > +static int hsw_runtime_suspend(struct drm_i915_private *dev_priv)
> >  {
> >         hsw_enable_pc8(dev_priv);
> > +
> > +       return 0;
> >  }
> >
> > -static void snb_runtime_resume(struct drm_i915_private *dev_priv)
> > +static int snb_runtime_resume(struct drm_i915_private *dev_priv)
> >  {
> >         struct drm_device *dev = dev_priv->dev;
> >
> > @@ -913,11 +917,15 @@ static void snb_runtime_resume(struct drm_i915_private *dev_priv)
> >         mutex_lock(&dev_priv->rps.hw_lock);
> >         gen6_update_ring_freq(dev);
> >         mutex_unlock(&dev_priv->rps.hw_lock);
> > +
> > +       return 0;
> >  }
> >
> > -static void hsw_runtime_resume(struct drm_i915_private *dev_priv)
> > +static int hsw_runtime_resume(struct drm_i915_private *dev_priv)
> >  {
> >         hsw_disable_pc8(dev_priv);
> > +
> > +       return 0;
> >  }
> >
> >  /*
> > @@ -1144,11 +1152,155 @@ int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool force_on)
> >  #undef COND
> >  }
> >
> > +static int vlv_allow_gt_wake(struct drm_i915_private *dev_priv, bool allow)
> > +{
> > +       u32 val;
> > +       int err = 0;
> > +
> > +       val = I915_READ(VLV_GTLC_WAKE_CTRL);
> > +       val &= ~VLV_GTLC_ALLOWWAKEREQ;
> > +       if (allow)
> > +               val |= VLV_GTLC_ALLOWWAKEREQ;
> > +       I915_WRITE(VLV_GTLC_WAKE_CTRL, val);
> > +       POSTING_READ(VLV_GTLC_WAKE_CTRL);
> > +
> > +#define COND (!!(I915_READ(VLV_GTLC_PW_STATUS) & VLV_GTLC_ALLOWWAKEACK) == \
> > +             allow)
> > +       err = wait_for(COND, 1);
> > +       if (err)
> > +               DRM_ERROR("timeout disabling GT waking\n");
> > +       return err;
> > +#undef COND
> > +}
> > +
> > +static int vlv_wait_for_gt_wells(struct drm_i915_private *dev_priv,
> > +                                bool wait_for_on)
> > +{
> > +       u32 mask;
> > +       u32 val;
> > +       int err;
> > +
> > +       mask = VLV_GTLC_PW_MEDIA_STATUS_MASK | VLV_GTLC_PW_RENDER_STATUS_MASK;
> > +       val = wait_for_on ? mask : 0;
> > +#define COND ((I915_READ(VLV_GTLC_PW_STATUS) & mask) == val)
> > +       if (COND)
> > +               return 0;
> > +
> > +       DRM_DEBUG_KMS("waiting for GT wells to go %s (%08x)\n",
> > +                       wait_for_on ? "on" : "off",
> > +                       I915_READ(VLV_GTLC_PW_STATUS));
> > +
> > +       /*
> > +        * RC6 transitioning can be delayed up to 2 msec (see
> > +        * valleyview_enable_rps), use 3 msec for safety.
> > +        */
> > +       err = wait_for(COND, 3);
> > +       if (err)
> > +               DRM_ERROR("timeout waiting for GT wells to go %s\n",
> > +                         wait_for_on ? "on" : "off");
> > +
> > +       return err;
> > +#undef COND
> > +}
> > +
> > +static void vlv_check_no_gt_access(struct drm_i915_private *dev_priv)
> > +{
> > +       if (!(I915_READ(VLV_GTLC_PW_STATUS) & VLV_GTLC_ALLOWWAKEERR))
> > +               return;
> > +
> > +       DRM_ERROR("GT register access while GT waking disabled\n");
> > +       I915_WRITE(VLV_GTLC_PW_STATUS, VLV_GTLC_ALLOWWAKEERR);
> > +}
> > +
> > +static int vlv_runtime_suspend(struct drm_i915_private *dev_priv)
> > +{
> > +       struct drm_device *dev = dev_priv->dev;
> > +       u32 mask;
> > +       int err;
> > +
> > +       if (WARN_ON(!valleyview_rc6_enabled(dev)))
> > +               return -ENODEV;
> > +
> > +       intel_runtime_pm_disable_interrupts(dev);
> > +       cancel_work_sync(&dev_priv->rps.work);
> > +
> > +       /*
> > +        * Bspec defines the following GT well on flags as debug only, so
> > +        * don't treat them as hard failures.
> > +        */
> > +       (void)vlv_wait_for_gt_wells(dev_priv, false);
> > +
> > +       mask = VLV_GTLC_RENDER_CTX_EXISTS | VLV_GTLC_MEDIA_CTX_EXISTS;
> > +       WARN_ON((I915_READ(VLV_GTLC_WAKE_CTRL) & mask) != mask);
> > +
> > +       vlv_check_no_gt_access(dev_priv);
> > +
> > +       err = vlv_force_gfx_clock(dev_priv, true);
> > +       if (err)
> > +               goto err1;
> > +
> > +       err = vlv_allow_gt_wake(dev_priv, false);
> > +       if (err)
> > +               goto err2;
> > +       vlv_save_gunit_s0ix_state(dev_priv);
> > +
> > +       err = vlv_force_gfx_clock(dev_priv, false);
> > +       if (err)
> > +               goto err2;
> > +
> > +       return 0;
> > +
> > +err2:
> > +       /* For safety always re-enable waking and disable gfx clock forcing */
> > +       vlv_allow_gt_wake(dev_priv, true);
> > +err1:
> > +       vlv_force_gfx_clock(dev_priv, false);
> > +       intel_runtime_pm_restore_interrupts(dev);
> > +
> > +       return err;
> > +}
> > +
> > +static int vlv_runtime_resume(struct drm_i915_private *dev_priv)
> > +{
> > +       struct drm_device *dev = dev_priv->dev;
> > +       int err;
> > +       int ret;
> > +
> > +       /*
> > +        * If any of the steps fail just try to continue, that's the best we
> > +        * can do at this point. Return the first error code (which will also
> > +        * leave RPM permanentyl disabled).
> > +        */
> > +       ret = vlv_force_gfx_clock(dev_priv, true);
> > +
> > +       vlv_restore_gunit_s0ix_state(dev_priv);
> > +
> > +       err = vlv_allow_gt_wake(dev_priv, true);
> > +       if (!ret)
> > +               ret = err;
> > +
> > +       err = vlv_force_gfx_clock(dev_priv, false);
> > +       if (!ret)
> > +               ret = err;
> > +
> > +       vlv_check_no_gt_access(dev_priv);
> > +
> > +       intel_init_clock_gating(dev);
> > +       intel_reset_gt_powersave(dev);
> > +       i915_gem_init_swizzling(dev);
> > +       i915_gem_restore_fences(dev);
> > +
> > +       intel_runtime_pm_restore_interrupts(dev);
> > +
> > +       return ret;
> > +}
> > +
> >  static int intel_runtime_suspend(struct device *device)
> >  {
> >         struct pci_dev *pdev = to_pci_dev(device);
> >         struct drm_device *dev = pci_get_drvdata(pdev);
> >         struct drm_i915_private *dev_priv = dev->dev_private;
> > +       int ret = 0;
> >
> >         if (WARN_ON_ONCE(!dev_priv->rps.enabled))
> >                 return -ENODEV;
> > @@ -1162,9 +1314,17 @@ static int intel_runtime_suspend(struct device *device)
> >                 snb_runtime_suspend(dev_priv);
> >         else if (IS_HASWELL(dev) || IS_BROADWELL(dev))
> >                 hsw_runtime_suspend(dev_priv);
> 
> You make these guys return an error code, but you don't check for
> them. Even if they always return 0, I think it's good to add the check
> now, because in the future someone may write a patch adding a non-zero
> return and forget to add code to check for the error.

Yep, I missed that.

I actually depend on these propagating the error from the VLV callbacks,
since those can fail.

BTW, right now I'm leaving RPM permanently disabled in case of an error,
but I think we should try to reenable it.. Perhaps after a reset. I
wasn't sure what's the right policy here, but in any case this can be
added later as a follow-up if needed.

--Imre

> 
> > +       else if (IS_VALLEYVIEW(dev))
> > +               ret = vlv_runtime_suspend(dev_priv);
> >         else
> >                 WARN_ON(1);
> >
> > +       if (ret) {
> > +               DRM_ERROR("Runtime suspend failed, disabling it\n");
> > +
> > +               return ret;
> > +       }
> > +
> >         i915_gem_release_all_mmaps(dev_priv);
> >
> >         del_timer_sync(&dev_priv->gpu_error.hangcheck_timer);
> > @@ -1200,6 +1360,8 @@ static int intel_runtime_resume(struct device *device)
> >                 snb_runtime_resume(dev_priv);
> >         else if (IS_HASWELL(dev) || IS_BROADWELL(dev))
> >                 hsw_runtime_resume(dev_priv);
> > +       else if (IS_VALLEYVIEW(dev))
> > +               vlv_runtime_resume(dev_priv);
> 
> Same here.
> 
> >         else
> >                 WARN_ON(1);
> >
> > --
> > 1.8.4
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> 
>