Re: [PATCH] drm/i915/vlv: assert and de-assert sideband reset on resume

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Apr 11, 2014 at 10:00:16AM -0700, Jesse Barnes wrote:
> This is a bit like the CMN reset de-assert we do in DPIO_CTL, except
> that it resets the whole common lane section of the PHY.  This is
> required on machines where the BIOS doesn't do this for us on resume to
> properly re-calibrate and get the PHY ready to transmit data.
> 
> Without this patch, such machines won't resume correctly much of the time,
> with the symptom being a 'port ready' timeout and/or a link training
> failure.
> 
> I'm open to better suggestions on how to do the power well toggle, with
> the existing code it looks like I'd have to walk through a bunch of
> power domains looking for a match, then call a generic function which
> will warn.  I'd prefer to just expose the specific domains directly for
> low level platform code like this.
> 
> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> ---
>  drivers/gpu/drm/i915/intel_pm.c     |    4 ++--
>  drivers/gpu/drm/i915/intel_uncore.c |   19 +++++++++++++++++++
>  2 files changed, 21 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index fa00185..3afd0bc 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5454,8 +5454,8 @@ static bool i9xx_always_on_power_well_enabled(struct drm_i915_private *dev_priv,
>  	return true;
>  }
>  
> -static void vlv_set_power_well(struct drm_i915_private *dev_priv,
> -			       struct i915_power_well *power_well, bool enable)
> +void vlv_set_power_well(struct drm_i915_private *dev_priv,
> +			struct i915_power_well *power_well, bool enable)
>  {
>  	enum punit_power_well power_well_id = power_well->data;
>  	u32 mask;
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 2a72bab..f1abd2d 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -363,6 +363,9 @@ static void intel_uncore_forcewake_reset(struct drm_device *dev, bool restore)
>  	spin_unlock_irqrestore(&dev_priv->uncore.lock, irqflags);
>  }
>  
> +void vlv_set_power_well(struct drm_i915_private *dev_priv,
> +			struct i915_power_well *power_well, bool enable);
> +
>  void intel_uncore_early_sanitize(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -381,6 +384,22 @@ void intel_uncore_early_sanitize(struct drm_device *dev)
>  		DRM_INFO("Found %zuMB of eLLC\n", dev_priv->ellc_size);
>  	}
>  
> +	/*
> +	 * From VLV2A0_DP_eDP_HDMI_DPIO_driver_vbios_notes_11.docx:
> +	 * Need to assert and de-assert PHY SB reset by gating the common
> +	 * lane power, then un-gating it.
> +	 * Simply ungating isn't enough to reset the PHY enough to get
> +	 * ports and lanes running.
> +	 */
> +	if (IS_VALLEYVIEW(dev)) {
> +		struct i915_power_well cmn_well = {
> +			.data = PUNIT_POWER_WELL_DPIO_CMN_BC
> +		};
> +
> +		vlv_set_power_well(dev_priv, &cmn_well, false);
> +		vlv_set_power_well(dev_priv, &cmn_well, true);
> +	}

Stick this into intel_reset_dpio() instead?

And what about fastboot and whatnot? Should we check if the display is
already up and running somehow before we go and kill it with this?

> +
>  	/* clear out old GT FIFO errors */
>  	if (IS_GEN6(dev) || IS_GEN7(dev))
>  		__raw_i915_write32(dev_priv, GTFIFODBG,
> -- 
> 1.7.9.5
> 
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-- 
Ville Syrjälä
Intel OTC