Re: [Intel-gfx] [PATCH] drm/i915: Move the g45 PEG band gap HPD workaround to the HPD code

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 12 Oct 2023, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> We are asked to reprogram PEG_BAND_GAP_DATA prior to enabling
> hotplug detection on the g45 HDMI/DP ports. Currently we do said
> reprogamming from the DP/HDMI connector initialization functions.
> That code should be mostly platform agnostic so clearly not the
> best place for this. Move the workaround to the place where we
> actually enable HPD detection.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c          | 10 ----------
>  drivers/gpu/drm/i915/display/intel_hdmi.c        | 10 ----------
>  drivers/gpu/drm/i915/display/intel_hotplug_irq.c | 16 ++++++++++++++++
>  3 files changed, 16 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 4f6835a7578e..f2d6c4da72ab 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -6198,16 +6198,6 @@ intel_dp_init_connector(struct intel_digital_port *dig_port,
>  				    "HDCP init failed, skipping.\n");
>  	}
>  
> -	/* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
> -	 * 0xd.  Failure to do so will result in spurious interrupts being
> -	 * generated on the port when a cable is not attached.
> -	 */
> -	if (IS_G45(dev_priv)) {
> -		u32 temp = intel_de_read(dev_priv, PEG_BAND_GAP_DATA);
> -		intel_de_write(dev_priv, PEG_BAND_GAP_DATA,
> -			       (temp & ~0xf) | 0xd);
> -	}
> -
>  	intel_dp->frl.is_trained = false;
>  	intel_dp->frl.trained_rate_gbps = 0;
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
> index ac315f8e7820..ab18cfc19c0a 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
> @@ -3030,16 +3030,6 @@ void intel_hdmi_init_connector(struct intel_digital_port *dig_port,
>  				    "HDCP init failed, skipping.\n");
>  	}
>  
> -	/* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
> -	 * 0xd.  Failure to do so will result in spurious interrupts being
> -	 * generated on the port when a cable is not attached.
> -	 */
> -	if (IS_G45(dev_priv)) {
> -		u32 temp = intel_de_read(dev_priv, PEG_BAND_GAP_DATA);
> -		intel_de_write(dev_priv, PEG_BAND_GAP_DATA,
> -		               (temp & ~0xf) | 0xd);
> -	}
> -
>  	cec_fill_conn_info_from_drm(&conn_info, connector);
>  
>  	intel_hdmi->cec_notifier =
> diff --git a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
> index f07047e9cb30..04f62f27ad74 100644
> --- a/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
> +++ b/drivers/gpu/drm/i915/display/intel_hotplug_irq.c
> @@ -1361,11 +1361,24 @@ static void bxt_hpd_irq_setup(struct drm_i915_private *dev_priv)
>  	bxt_hpd_detection_setup(dev_priv);
>  }
>  
> +static void g45_hpd_peg_band_gap_wa(struct drm_i915_private *i915)
> +{
> +	/*
> +	 * For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
> +	 * 0xd.  Failure to do so will result in spurious interrupts being
> +	 * generated on the port when a cable is not attached.
> +	 */
> +	intel_de_rmw(i915, PEG_BAND_GAP_DATA, 0xf, 0xd);
> +}
> +
>  static void i915_hpd_enable_detection(struct intel_encoder *encoder)
>  {
>  	struct drm_i915_private *i915 = to_i915(encoder->base.dev);
>  	u32 hotplug_en = hpd_mask_i915[encoder->hpd_pin];
>  
> +	if (IS_G45(i915))
> +		g45_hpd_peg_band_gap_wa(i915);
> +
>  	/* HPD sense and interrupt enable are one and the same */
>  	i915_hotplug_interrupt_update(i915, hotplug_en, hotplug_en);
>  }
> @@ -1389,6 +1402,9 @@ static void i915_hpd_irq_setup(struct drm_i915_private *dev_priv)
>  		hotplug_en |= CRT_HOTPLUG_ACTIVATION_PERIOD_64;
>  	hotplug_en |= CRT_HOTPLUG_VOLTAGE_COMPARE_50;
>  
> +	if (IS_G45(dev_priv))
> +		g45_hpd_peg_band_gap_wa(dev_priv);
> +
>  	/* Ignore TV since it's buggy */
>  	i915_hotplug_interrupt_update_locked(dev_priv,
>  					     HOTPLUG_INT_EN_MASK |

-- 
Jani Nikula, Intel