Re: [PATCH 1/4] drm/i915/gen9+: Enable hotplug detection early

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

On Sat, Jan 28, 2017 at 10:24:19AM +0530, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 1/27/2017 3:09 PM, Imre Deak wrote:
> >For LSPCON resume time initialization we need to sample the
> >corresponding pin's HPD level, but this is only available when HPD
> >detection is enabled. Currently we enable detection only when enabling
> >HPD interrupts which is too late, so bring the enabling of detection
> >earlier.
> >
> >This is needed by the next patch.
> >
> >Cc: Shashank Sharma <shashank.sharma@intel.com>
> >Cc: Jani Nikula <jani.nikula@linux.intel.com>
> >Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> >Cc: <stable@vger.kernel.org> # v4.9+
> >Signed-off-by: Imre Deak <imre.deak@intel.com>
> >---
> >  drivers/gpu/drm/i915/i915_irq.c | 71 +++++++++++++++++++++++++++++------------
> >  1 file changed, 51 insertions(+), 20 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> >index 8440d8b..6daf522 100644
> >--- a/drivers/gpu/drm/i915/i915_irq.c
> >+++ b/drivers/gpu/drm/i915/i915_irq.c
> >@@ -3142,24 +3142,33 @@ static void ibx_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >  	I915_WRITE(PCH_PORT_HOTPLUG, hotplug);
> >  }
> >+static void spt_hpd_detection_setup(struct drm_i915_private *dev_priv)
> >+{
> >+	u32 hotplug;
> >+
> >+	/* Enable digital hotplug on the PCH */
> >+	hotplug = I915_READ(PCH_PORT_HOTPLUG);
> >+	hotplug |= PORTA_HOTPLUG_ENABLE |
> >+		   PORTB_HOTPLUG_ENABLE |
> >+		   PORTC_HOTPLUG_ENABLE |
> >+		   PORTD_HOTPLUG_ENABLE;
> >+	I915_WRITE(PCH_PORT_HOTPLUG, hotplug);
> >+
> >+	hotplug = I915_READ(PCH_PORT_HOTPLUG2);
> >+	hotplug |= PORTE_HOTPLUG_ENABLE;
> >+	I915_WRITE(PCH_PORT_HOTPLUG2, hotplug);
> >+}
> >+
> >  static void spt_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >  {
> >-	u32 hotplug_irqs, hotplug, enabled_irqs;
> >+	u32 hotplug_irqs, enabled_irqs;
> >  	hotplug_irqs = SDE_HOTPLUG_MASK_SPT;
> >  	enabled_irqs = intel_hpd_enabled_irqs(dev_priv, hpd_spt);
> >  	ibx_display_interrupt_update(dev_priv, hotplug_irqs, enabled_irqs);
> >-	/* Enable digital hotplug on the PCH */
> >-	hotplug = I915_READ(PCH_PORT_HOTPLUG);
> >-	hotplug |= PORTD_HOTPLUG_ENABLE | PORTC_HOTPLUG_ENABLE |
> >-		PORTB_HOTPLUG_ENABLE | PORTA_HOTPLUG_ENABLE;
> >-	I915_WRITE(PCH_PORT_HOTPLUG, hotplug);
> >-
> >-	hotplug = I915_READ(PCH_PORT_HOTPLUG2);
> >-	hotplug |= PORTE_HOTPLUG_ENABLE;
> >-	I915_WRITE(PCH_PORT_HOTPLUG2, hotplug);
> >+	spt_hpd_detection_setup(dev_priv);
> >  }
> >  static void ilk_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >@@ -3196,18 +3205,15 @@ static void ilk_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >  	ibx_hpd_irq_setup(dev_priv);
> >  }
> >-static void bxt_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >+static void __bxt_hpd_detection_setup(struct drm_i915_private *dev_priv,
> >+					     u32 enabled_irqs)
> >  {
> >-	u32 hotplug_irqs, hotplug, enabled_irqs;
> >-
> >-	enabled_irqs = intel_hpd_enabled_irqs(dev_priv, hpd_bxt);
> >-	hotplug_irqs = BXT_DE_PORT_HOTPLUG_MASK;
> >-
> >-	bdw_update_port_irq(dev_priv, hotplug_irqs, enabled_irqs);
> >+	u32 hotplug;
> >  	hotplug = I915_READ(PCH_PORT_HOTPLUG);
> >-	hotplug |= PORTC_HOTPLUG_ENABLE | PORTB_HOTPLUG_ENABLE |
> >-		PORTA_HOTPLUG_ENABLE;
> >+	hotplug |= PORTA_HOTPLUG_ENABLE |
> >+		   PORTB_HOTPLUG_ENABLE |
> >+		   PORTC_HOTPLUG_ENABLE;
> >  	DRM_DEBUG_KMS("Invert bit setting: hp_ctl:%x hp_port:%x\n",
> >  		      hotplug, enabled_irqs);
> >@@ -3217,7 +3223,6 @@ static void bxt_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >  	 * For BXT invert bit has to be set based on AOB design
> >  	 * for HPD detection logic, update it based on VBT fields.
> >  	 */
> >-
> >  	if ((enabled_irqs & BXT_DE_PORT_HP_DDIA) &&
> >  	    intel_bios_is_port_hpd_inverted(dev_priv, PORT_A))
> >  		hotplug |= BXT_DDIA_HPD_INVERT;
> >@@ -3231,6 +3236,23 @@ static void bxt_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >  	I915_WRITE(PCH_PORT_HOTPLUG, hotplug);
> >  }
> >+static void bxt_hpd_detection_setup(struct drm_i915_private *dev_priv)
> >+{
> >+	__bxt_hpd_detection_setup(dev_priv, BXT_DE_PORT_HOTPLUG_MASK);
> Do we need another layer of internal function ? Why cant the content of
> __bxt_hpd_detection_setup be here, just
> like spd_hpd_detection_setup, as they both are static to the file ?

The port configuration is platform specific and so I wanted to keep it
close to where the rest of HPD setup is done. The caller of
bxt_hpd_detection_setup() only cares about enabling detection on _all_
ports as the other *_hpd_detection_setup() helpers.

> >+}
> >+
> >+static void bxt_hpd_irq_setup(struct drm_i915_private *dev_priv)
> >+{
> >+	u32 hotplug_irqs, enabled_irqs;
> >+
> >+	enabled_irqs = intel_hpd_enabled_irqs(dev_priv, hpd_bxt);
> >+	hotplug_irqs = BXT_DE_PORT_HOTPLUG_MASK;
> >+
> >+	bdw_update_port_irq(dev_priv, hotplug_irqs, enabled_irqs);
> >+
> >+	__bxt_hpd_detection_setup(dev_priv, enabled_irqs);
> >+}
> >+
> >  static void ibx_irq_postinstall(struct drm_device *dev)
> >  {
> >  	struct drm_i915_private *dev_priv = to_i915(dev);
> >@@ -3246,6 +3268,12 @@ static void ibx_irq_postinstall(struct drm_device *dev)
> >  	gen5_assert_iir_is_zero(dev_priv, SDEIIR);
> >  	I915_WRITE(SDEIMR, ~mask);
> >+
> >+	if (HAS_PCH_IBX(dev_priv) || HAS_PCH_CPT(dev_priv) ||
> >+	    HAS_PCH_LPT(dev_priv))
> >+		; /* TODO: Enable HPD detection on older PCH platforms too */
> >+	else
> >+		spt_hpd_detection_setup(dev_priv);
> >  }
> >  static void gen5_gt_irq_postinstall(struct drm_device *dev)
> >@@ -3457,6 +3485,9 @@ static void gen8_de_irq_postinstall(struct drm_i915_private *dev_priv)
> >  	GEN5_IRQ_INIT(GEN8_DE_PORT_, ~de_port_masked, de_port_enables);
> >  	GEN5_IRQ_INIT(GEN8_DE_MISC_, ~de_misc_masked, de_misc_masked);
> >+
> >+	if (IS_GEN9_LP(dev_priv))
> I have not done the delta analysis between hotplug interrupts, but this will
> be true for GLK too.
> Should we bother ?

The GLK HPD detection setup and interrupt setup and handling is the same as
on BXT. See bxt_hpd_irq_setup() and bxt_hpd_irq_handler() that are
called on GLK as well.

> 
> - Shashank
> >+		bxt_hpd_detection_setup(dev_priv);
> >  }
> >  static int gen8_irq_postinstall(struct drm_device *dev)
> 
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