Re: [PATCH 15/15] drm/i915: Add CHV PHY LDO power sanity checks

[Deepak <deepak.s@linux.intel.com>]

On 07/09/2015 02:16 AM, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> At various points when changing the DPIO lane/phy power states,
> construct an expected value of the DISPLAY_PHY_STATUS register
> and compare it with the real thing.
>
> To construct the expected value we look at our shadow PHY_CONTROL
> register value (which should match what we've just written to the
> hardware), and we also need to look at the actual state of the cmn
> power wells as a disabled power well causes the relevant LDO status
> to be reported as 'on' in DISPLAY_PHY_STATUS.
>
> When initially powering up the PHY it performs various internal
> calibrations for which it fully powers up. That means that if we check
> for the expetected power state immediately upon releasing cmnreset we
> would get the occasional false positive. But we can of course
> poll until the expected value appears. It shouldn't be too long so
> this shouldn't make modesets substantially longer.
>
> One extra complication is introduced when we cross the streams, ie.
> drive port B with pipe B. In this case we trick CL2 (where the DPLL lives)
> into life by temporaily powering up the lanes in the second channel,
> and once the pipe is up and runnign we release the lane power override.
> At that point the power state of CL2 has somehow gotten entangled with
> the power state of the first channel. That means that constructing the
> expected DISPLAY_PHY_STATUS value is a bit tricky since based on the
> lane power states in the second channel, CL2 should also be powered
> down. But we can use the DPLL enable bit to determine when CL2 should
> be alive even if the lanes are powered down. However the power state
> of CL2 isn't actually tied in with the DPLL state, but to the state
> of the lanes in first channel, so we have to avoid checking the
> expected state between shutting down the DPLL and powering down
> the lanes in the first channel. So no calling assert_chv_phy_status()
> before the DISPLAY_PHY_CONTROL write in chv_phy_powergate_lanes(),
> but after the write is a safe time to check.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>   drivers/gpu/drm/i915/i915_reg.h         |   2 +
>   drivers/gpu/drm/i915/intel_runtime_pm.c | 126 +++++++++++++++++++++++++++-----
>   2 files changed, 111 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 586a0f7..429105e 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -2206,6 +2206,8 @@ enum skl_disp_power_wells {
>   #define   PHY_COM_LANE_RESET_DEASSERT(phy)	(1 << (phy))
>   #define DISPLAY_PHY_STATUS (VLV_DISPLAY_BASE + 0x60104)
>   #define   PHY_POWERGOOD(phy)	(((phy) == DPIO_PHY0) ? (1<<31) : (1<<30))
> +#define   PHY_STATUS_CMN_LDO(phy, ch)                   (1 << (6-(6*(phy)+3*(ch))))
> +#define   PHY_STATUS_SPLINE_LDO(phy, ch, spline)        (1 << (8-(6*(phy)+3*(ch)+(spline))))
>   
>   /*
>    * The i830 generation, in LVDS mode, defines P1 as the bit number set within
> diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
> index a1d9676..e6f1b4ee 100644
> --- a/drivers/gpu/drm/i915/intel_runtime_pm.c
> +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
> @@ -942,6 +942,107 @@ static void vlv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
>   	vlv_set_power_well(dev_priv, power_well, false);
>   }
>   
> +#define POWER_DOMAIN_MASK (BIT(POWER_DOMAIN_NUM) - 1)
> +
> +static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_priv,
> +						 int power_well_id)
> +{
> +	struct i915_power_domains *power_domains = &dev_priv->power_domains;
> +	struct i915_power_well *power_well;
> +	int i;
> +
> +	for_each_power_well(i, power_well, POWER_DOMAIN_MASK, power_domains) {
> +		if (power_well->data == power_well_id)
> +			return power_well;
> +	}
> +
> +	return NULL;
> +}
> +
> +#define BITS_SET(val, bits) (((val) & (bits)) == (bits))
> +
> +static void assert_chv_phy_status(struct drm_i915_private *dev_priv)
> +{
> +	struct i915_power_well *cmn_bc =
> +		lookup_power_well(dev_priv, PUNIT_POWER_WELL_DPIO_CMN_BC);
> +	struct i915_power_well *cmn_d =
> +		lookup_power_well(dev_priv, PUNIT_POWER_WELL_DPIO_CMN_D);
> +	u32 phy_control = dev_priv->chv_phy_control;
> +	u32 phy_status = 0;
> +	u32 tmp;
> +
> +	if (cmn_bc->ops->is_enabled(dev_priv, cmn_bc)) {
> +		phy_status |= PHY_POWERGOOD(DPIO_PHY0);
> +
> +		/* this assumes override is only used to enable lanes */
> +		if ((phy_control & PHY_CH_POWER_DOWN_OVRD_EN(DPIO_PHY0, DPIO_CH0)) == 0)
> +			phy_control |= PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH0);
> +
> +		if ((phy_control & PHY_CH_POWER_DOWN_OVRD_EN(DPIO_PHY0, DPIO_CH1)) == 0)
> +			phy_control |= PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH1);
> +
> +		/* CL1 is on whenever anything is on in either channel */
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH0) |
> +			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH1)))
> +			phy_status |= PHY_STATUS_CMN_LDO(DPIO_PHY0, DPIO_CH0);
> +
> +		/*
> +		 * The DPLLB check accounts for the pipe B + port A usage
> +		 * with CL2 powered up but all the lanes in the second channel
> +		 * powered down.
> +		 */
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY0, DPIO_CH1)) &&
> +		    (I915_READ(DPLL(PIPE_B)) & DPLL_VCO_ENABLE) == 0)
> +			phy_status |= PHY_STATUS_CMN_LDO(DPIO_PHY0, DPIO_CH1);
> +
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0x3, DPIO_PHY0, DPIO_CH0)))
> +			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH0, 0);
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0xc, DPIO_PHY0, DPIO_CH0)))
> +			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH0, 1);
> +
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0x3, DPIO_PHY0, DPIO_CH1)))
> +			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH1, 0);
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0xc, DPIO_PHY0, DPIO_CH1)))
> +			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY0, DPIO_CH1, 1);
> +	}
> +
> +	if (cmn_d->ops->is_enabled(dev_priv, cmn_d)) {
> +		phy_status |= PHY_POWERGOOD(DPIO_PHY1);
> +
> +		/* this assumes override is only used to enable lanes */
> +		if ((phy_control & PHY_CH_POWER_DOWN_OVRD_EN(DPIO_PHY1, DPIO_CH0)) == 0)
> +			phy_control |= PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY1, DPIO_CH0);
> +
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0xf, DPIO_PHY1, DPIO_CH0)))
> +			phy_status |= PHY_STATUS_CMN_LDO(DPIO_PHY1, DPIO_CH0);
> +
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0x3, DPIO_PHY1, DPIO_CH0)))
> +			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY1, DPIO_CH0, 0);
> +		if (BITS_SET(phy_control,
> +			     PHY_CH_POWER_DOWN_OVRD(0xc, DPIO_PHY1, DPIO_CH0)))
> +			phy_status |= PHY_STATUS_SPLINE_LDO(DPIO_PHY1, DPIO_CH0, 1);
> +	}
> +
> +	/*
> +	 * The PHY may be busy with some initial calibration and whatnot,
> +	 * so the power state can take a while to actually change.
> +	 */
> +	if (wait_for((tmp = I915_READ(DISPLAY_PHY_STATUS)) == phy_status, 10))
> +		WARN(phy_status != tmp,
> +		     "Unexpected PHY_STATUS 0x%08x, expected 0x%08x (PHY_CONTROL=0x%08x)\n",
> +		     tmp, phy_status, dev_priv->chv_phy_control);
> +}
> +
> +#undef BITS_SET
> +
>   static void chv_dpio_cmn_power_well_enable(struct drm_i915_private *dev_priv,
>   					   struct i915_power_well *power_well)
>   {
> @@ -998,6 +1099,8 @@ static void chv_dpio_cmn_power_well_enable(struct drm_i915_private *dev_priv,
>   
>   	DRM_DEBUG_KMS("Enabled DPIO PHY%d (PHY_CONTROL=0x%08x)\n",
>   		      phy, dev_priv->chv_phy_control);
> +
> +	assert_chv_phy_status(dev_priv);
>   }
>   
>   static void chv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
> @@ -1024,6 +1127,8 @@ static void chv_dpio_cmn_power_well_disable(struct drm_i915_private *dev_priv,
>   
>   	DRM_DEBUG_KMS("Disabled DPIO PHY%d (PHY_CONTROL=0x%08x)\n",
>   		      phy, dev_priv->chv_phy_control);
> +
> +	assert_chv_phy_status(dev_priv);
>   }
>   
>   static void assert_chv_phy_powergate(struct drm_i915_private *dev_priv, enum dpio_phy phy,
> @@ -1101,6 +1206,8 @@ bool chv_phy_powergate_ch(struct drm_i915_private *dev_priv, enum dpio_phy phy,
>   	DRM_DEBUG_KMS("Power gating DPIO PHY%d CH%d (DPIO_PHY_CONTROL=0x%08x)\n",
>   		      phy, ch, dev_priv->chv_phy_control);
>   
> +	assert_chv_phy_status(dev_priv);
> +
>   out:
>   	mutex_unlock(&power_domains->lock);
>   
> @@ -1130,6 +1237,8 @@ void chv_phy_powergate_lanes(struct intel_encoder *encoder,
>   	DRM_DEBUG_KMS("Power gating DPIO PHY%d CH%d lanes 0x%x (PHY_CONTROL=0x%08x)\n",
>   		      phy, ch, mask, dev_priv->chv_phy_control);
>   
> +	assert_chv_phy_status(dev_priv);
> +
Patch looks fine with assertion at right places
Reviewed-by: Deepak S <deepak.s@linux.intel.com>
>   	assert_chv_phy_powergate(dev_priv, phy, ch, override, mask);
>   
>   	mutex_unlock(&power_domains->lock);
> @@ -1302,8 +1411,6 @@ void intel_display_power_put(struct drm_i915_private *dev_priv,
>   	intel_runtime_pm_put(dev_priv);
>   }
>   
> -#define POWER_DOMAIN_MASK (BIT(POWER_DOMAIN_NUM) - 1)
> -
>   #define HSW_ALWAYS_ON_POWER_DOMAINS (			\
>   	BIT(POWER_DOMAIN_PIPE_A) |			\
>   	BIT(POWER_DOMAIN_TRANSCODER_EDP) |		\
> @@ -1565,21 +1672,6 @@ static struct i915_power_well chv_power_wells[] = {
>   	},
>   };
>   
> -static struct i915_power_well *lookup_power_well(struct drm_i915_private *dev_priv,
> -						 int power_well_id)
> -{
> -	struct i915_power_domains *power_domains = &dev_priv->power_domains;
> -	struct i915_power_well *power_well;
> -	int i;
> -
> -	for_each_power_well(i, power_well, POWER_DOMAIN_MASK, power_domains) {
> -		if (power_well->data == power_well_id)
> -			return power_well;
> -	}
> -
> -	return NULL;
> -}
> -
>   bool intel_display_power_well_is_enabled(struct drm_i915_private *dev_priv,
>   				    int power_well_id)
>   {

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