Re: [PATCH RESEND 2/5] drm/i915: move VBT based LVDS presence check to intel_bios.c

["Thulasimani, Sivakumar" <sivakumar.thulasimani@intel.com>]

On 2/5/2016 4:06 PM, Jani Nikula wrote:
> Hide knowledge about VBT child devices in intel_bios.c.
>
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_drv.h   |  1 +
>   drivers/gpu/drm/i915/intel_bios.c | 50 ++++++++++++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/intel_lvds.c | 53 +--------------------------------------
>   3 files changed, 52 insertions(+), 52 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 715f200cfbf5..d70ef71d2538 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3398,6 +3398,7 @@ extern void intel_i2c_reset(struct drm_device *dev);
>   int intel_bios_init(struct drm_i915_private *dev_priv);
>   bool intel_bios_is_valid_vbt(const void *buf, size_t size);
>   bool intel_bios_is_tv_present(struct drm_i915_private *dev_priv);
> +bool intel_bios_is_lvds_present(struct drm_i915_private *dev_priv, u8 *i2c_pin);
>   
>   /* intel_opregion.c */
>   #ifdef CONFIG_ACPI
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index 2800ae50465a..f3f4f8e687cf 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -1469,3 +1469,53 @@ bool intel_bios_is_tv_present(struct drm_i915_private *dev_priv)
>   
>   	return false;
>   }
> +
> +/**
> + * intel_bios_is_lvds_present - is LVDS present in VBT
> + * @dev_priv:	i915 device instance
> + * @i2c_pin:	i2c pin for LVDS if present
> + *
> + * Return true if LVDS is present. If no child devices were parsed from VBT,
> + * assume LVDS is present.
> + */
> +bool intel_bios_is_lvds_present(struct drm_i915_private *dev_priv, u8 *i2c_pin)
> +{
> +	int i;
> +
> +	if (!dev_priv->vbt.child_dev_num)
> +		return true;
> +
we check if eDP is supported through following code before the call to
this function. please add this check here so we can avoid vbt 
referencing for that.

intel_lvds.c
  972         if (HAS_PCH_SPLIT(dev)) {
  973                 if ((lvds & LVDS_DETECTED) == 0)
  974                         return;
  975                 if (dev_priv->vbt.edp_support) {
  976                         DRM_DEBUG_KMS("disable LVDS for eDP 
support\n");
  977                         return;
  978                 }
  979         }

Sivakumar
> +	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
> +		union child_device_config *uchild = dev_priv->vbt.child_dev + i;
> +		struct old_child_dev_config *child = &uchild->old;
> +
> +		/* If the device type is not LFP, continue.
> +		 * We have to check both the new identifiers as well as the
> +		 * old for compatibility with some BIOSes.
> +		 */
> +		if (child->device_type != DEVICE_TYPE_INT_LFP &&
> +		    child->device_type != DEVICE_TYPE_LFP)
> +			continue;
> +
> +		if (intel_gmbus_is_valid_pin(dev_priv, child->i2c_pin))
> +			*i2c_pin = child->i2c_pin;
> +
> +		/* However, we cannot trust the BIOS writers to populate
> +		 * the VBT correctly.  Since LVDS requires additional
> +		 * information from AIM blocks, a non-zero addin offset is
> +		 * a good indicator that the LVDS is actually present.
> +		 */
> +		if (child->addin_offset)
> +			return true;
> +
> +		/* But even then some BIOS writers perform some black magic
> +		 * and instantiate the device without reference to any
> +		 * additional data.  Trust that if the VBT was written into
> +		 * the OpRegion then they have validated the LVDS's existence.
> +		 */
> +		if (dev_priv->opregion.vbt)
> +			return true;
> +	}
> +
> +	return false;
> +}
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index 0da0240caf81..80f8684e5137 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -772,57 +772,6 @@ static const struct dmi_system_id intel_no_lvds[] = {
>   	{ }	/* terminating entry */
>   };
>   
> -/*
> - * Enumerate the child dev array parsed from VBT to check whether
> - * the LVDS is present.
> - * If it is present, return 1.
> - * If it is not present, return false.
> - * If no child dev is parsed from VBT, it assumes that the LVDS is present.
> - */
> -static bool lvds_is_present_in_vbt(struct drm_device *dev,
> -				   u8 *i2c_pin)
> -{
> -	struct drm_i915_private *dev_priv = dev->dev_private;
> -	int i;
> -
> -	if (!dev_priv->vbt.child_dev_num)
> -		return true;
> -
> -	for (i = 0; i < dev_priv->vbt.child_dev_num; i++) {
> -		union child_device_config *uchild = dev_priv->vbt.child_dev + i;
> -		struct old_child_dev_config *child = &uchild->old;
> -
> -		/* If the device type is not LFP, continue.
> -		 * We have to check both the new identifiers as well as the
> -		 * old for compatibility with some BIOSes.
> -		 */
> -		if (child->device_type != DEVICE_TYPE_INT_LFP &&
> -		    child->device_type != DEVICE_TYPE_LFP)
> -			continue;
> -
> -		if (intel_gmbus_is_valid_pin(dev_priv, child->i2c_pin))
> -			*i2c_pin = child->i2c_pin;
> -
> -		/* However, we cannot trust the BIOS writers to populate
> -		 * the VBT correctly.  Since LVDS requires additional
> -		 * information from AIM blocks, a non-zero addin offset is
> -		 * a good indicator that the LVDS is actually present.
> -		 */
> -		if (child->addin_offset)
> -			return true;
> -
> -		/* But even then some BIOS writers perform some black magic
> -		 * and instantiate the device without reference to any
> -		 * additional data.  Trust that if the VBT was written into
> -		 * the OpRegion then they have validated the LVDS's existence.
> -		 */
> -		if (dev_priv->opregion.vbt)
> -			return true;
> -	}
> -
> -	return false;
> -}
> -
>   static int intel_dual_link_lvds_callback(const struct dmi_system_id *id)
>   {
>   	DRM_INFO("Forcing lvds to dual link mode on %s\n", id->ident);
> @@ -979,7 +928,7 @@ void intel_lvds_init(struct drm_device *dev)
>   	}
>   
>   	pin = GMBUS_PIN_PANEL;
> -	if (!lvds_is_present_in_vbt(dev, &pin)) {
> +	if (!intel_bios_is_lvds_present(dev_priv, &pin)) {
>   		if ((lvds & LVDS_PORT_EN) == 0) {
>   			DRM_DEBUG_KMS("LVDS is not present in VBT\n");
>   			return;

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