Re: [PATCH 06/11 v3] drm/i915/intel_i2c: refactor using intel_gmbus_get_adapter

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Mar 26, 2012 at 10:26:45PM +0800, Daniel Kurtz wrote:
> Instead of letting other modules directly access the ->gmbus array,
> introduce a new API, intel_gmbus_get_adapter(), to lookup an i2c_adapter
> for a given gmbus pin pair identifier.  This API enables later refactoring
> of the gmbus pin pair list.
> 
> Note: The gmbus pin must be checked for validity before requesting the
> corresponding gmbus port.  This is especially true when using a pin that
> has been read from VBIOS, as an improperly or uninitialied BIOS might
> indicate '0' for the 'disabled' pin pair, which doesn't actually exist. In
> the case of an invalid pin, the driver falls back to using a safer default
> pin pair.
> 
> Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>

With the cavet of the patch ordering issue, this looks ok. One comment
below.

> ---
>  drivers/gpu/drm/i915/i915_drv.h    |    7 +++++++
>  drivers/gpu/drm/i915/intel_bios.c  |    4 ++--
>  drivers/gpu/drm/i915/intel_crt.c   |   14 ++++++++------
>  drivers/gpu/drm/i915/intel_dvo.c   |    6 +++---
>  drivers/gpu/drm/i915/intel_hdmi.c  |    9 ++++++---
>  drivers/gpu/drm/i915/intel_i2c.c   |    8 ++++++++
>  drivers/gpu/drm/i915/intel_lvds.c  |    7 ++++---
>  drivers/gpu/drm/i915/intel_modes.c |    3 ++-
>  drivers/gpu/drm/i915/intel_sdvo.c  |    9 +++++----
>  9 files changed, 45 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b132677..64e0ae1 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1346,6 +1346,13 @@ extern int i915_restore_state(struct drm_device *dev);
>  /* intel_i2c.c */
>  extern int intel_setup_gmbus(struct drm_device *dev);
>  extern void intel_teardown_gmbus(struct drm_device *dev);
> +extern inline bool intel_gmbus_is_port_valid(unsigned port)
> +{
> +	return (port >= GMBUS_PORT_SSC && port <= GMBUS_PORT_DPD);
> +}
> +
> +extern struct i2c_adapter *intel_gmbus_get_adapter(
> +		struct drm_i915_private *dev_priv, unsigned port);
>  extern void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed);
>  extern void intel_gmbus_force_bit(struct i2c_adapter *adapter, bool force_bit);
>  extern inline bool intel_gmbus_is_forced_bit(struct i2c_adapter *adapter)
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index e4317da..871aa27 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -372,11 +372,11 @@ parse_general_definitions(struct drm_i915_private *dev_priv,
>  		if (block_size >= sizeof(*general)) {
>  			int bus_pin = general->crt_ddc_gmbus_pin;
>  			DRM_DEBUG_KMS("crt_ddc_bus_pin: %d\n", bus_pin);
> -			if (bus_pin >= 1 && bus_pin <= 6)
> +			if (intel_gmbus_is_port_valid(bus_pin))
>  				dev_priv->crt_ddc_pin = bus_pin;
>  		} else {
>  			DRM_DEBUG_KMS("BDB_GD too small (%d). Invalid.\n",
> -				  block_size);
> +				      block_size);
>  		}
>  	}
>  }
> diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
> index 4d3d736..d54d232 100644
> --- a/drivers/gpu/drm/i915/intel_crt.c
> +++ b/drivers/gpu/drm/i915/intel_crt.c
> @@ -278,9 +278,10 @@ static bool intel_crt_detect_ddc(struct drm_connector *connector)
>  	if (intel_ddc_probe(&crt->base, dev_priv->crt_ddc_pin)) {
>  		struct edid *edid;
>  		bool is_digital = false;
> +		struct i2c_adapter *i2c;
>  
> -		edid = drm_get_edid(connector,
> -			&dev_priv->gmbus[dev_priv->crt_ddc_pin].adapter);
> +		i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->crt_ddc_pin);
> +		edid = drm_get_edid(connector, i2c);
>  		/*
>  		 * This may be a DVI-I connector with a shared DDC
>  		 * link between analog and digital outputs, so we
> @@ -483,15 +484,16 @@ static int intel_crt_get_modes(struct drm_connector *connector)
>  	struct drm_device *dev = connector->dev;
>  	struct drm_i915_private *dev_priv = dev->dev_private;
>  	int ret;
> +	struct i2c_adapter *i2c;
>  
> -	ret = intel_ddc_get_modes(connector,
> -				 &dev_priv->gmbus[dev_priv->crt_ddc_pin].adapter);
> +	i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->crt_ddc_pin);
> +	ret = intel_ddc_get_modes(connector, i2c);
>  	if (ret || !IS_G4X(dev))
>  		return ret;
>  
>  	/* Try to probe digital port for output in DVI-I -> VGA mode. */
> -	return intel_ddc_get_modes(connector,
> -				   &dev_priv->gmbus[GMBUS_PORT_DPB].adapter);
> +	i2c = intel_gmbus_get_adapter(dev_priv, GMBUS_PORT_DPB);
> +	return intel_ddc_get_modes(connector, i2c);
>  }
>  
>  static int intel_crt_set_property(struct drm_connector *connector,
> diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c
> index 020a7d7..60ba50b9 100644
> --- a/drivers/gpu/drm/i915/intel_dvo.c
> +++ b/drivers/gpu/drm/i915/intel_dvo.c
> @@ -243,7 +243,7 @@ static int intel_dvo_get_modes(struct drm_connector *connector)
>  	 * that's not the case.
>  	 */
>  	intel_ddc_get_modes(connector,
> -			    &dev_priv->gmbus[GMBUS_PORT_DPC].adapter);
> +			    intel_gmbus_get_adapter(dev_priv, GMBUS_PORT_DPC));
>  	if (!list_empty(&connector->probed_modes))
>  		return 1;
>  
> @@ -375,7 +375,7 @@ void intel_dvo_init(struct drm_device *dev)
>  		 * special cases, but otherwise default to what's defined
>  		 * in the spec.
>  		 */
> -		if (dvo->gpio != 0)
> +		if (intel_gmbus_is_port_valid(dvo->gpio))
>  			gpio = dvo->gpio;
>  		else if (dvo->type == INTEL_DVO_CHIP_LVDS)
>  			gpio = GMBUS_PORT_SSC;
> @@ -386,7 +386,7 @@ void intel_dvo_init(struct drm_device *dev)
>  		 * It appears that everything is on GPIOE except for panels
>  		 * on i830 laptops, which are on GPIOB (DVOA).
>  		 */
> -		i2c = &dev_priv->gmbus[gpio].adapter;
> +		i2c = intel_gmbus_get_adapter(dev_priv, gpio);
>  
>  		intel_dvo->dev = *dvo;
>  		if (!dvo->dev_ops->init(&intel_dvo->dev, i2c))
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index cae3e5f..1d00f61 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -334,7 +334,8 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>  	intel_hdmi->has_hdmi_sink = false;
>  	intel_hdmi->has_audio = false;
>  	edid = drm_get_edid(connector,
> -			    &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
> +			    intel_gmbus_get_adapter(dev_priv,
> +						    intel_hdmi->ddc_bus));
>  
>  	if (edid) {
>  		if (edid->input & DRM_EDID_INPUT_DIGITAL) {
> @@ -367,7 +368,8 @@ static int intel_hdmi_get_modes(struct drm_connector *connector)
>  	 */
>  
>  	return intel_ddc_get_modes(connector,
> -				   &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
> +				   intel_gmbus_get_adapter(dev_priv,
> +							   intel_hdmi->ddc_bus));
>  }
>  
>  static bool
> @@ -379,7 +381,8 @@ intel_hdmi_detect_audio(struct drm_connector *connector)
>  	bool has_audio = false;
>  
>  	edid = drm_get_edid(connector,
> -			    &dev_priv->gmbus[intel_hdmi->ddc_bus].adapter);
> +			    intel_gmbus_get_adapter(dev_priv,
> +						    intel_hdmi->ddc_bus));
>  	if (edid) {
>  		if (edid->input & DRM_EDID_INPUT_DIGITAL)
>  			has_audio = drm_detect_monitor_audio(edid);
> diff --git a/drivers/gpu/drm/i915/intel_i2c.c b/drivers/gpu/drm/i915/intel_i2c.c
> index aa0670e..a04f773 100644
> --- a/drivers/gpu/drm/i915/intel_i2c.c
> +++ b/drivers/gpu/drm/i915/intel_i2c.c
> @@ -412,6 +412,14 @@ err:
>  	return ret;
>  }
>  
> +struct i2c_adapter *intel_gmbus_get_adapter(struct drm_i915_private *dev_priv,
> +					    unsigned port)
> +{
> +	BUG_ON(!intel_gmbus_is_port_valid(port));

WARN_ON highly preferred, safe when it's guaranteed that the code will
later on blow up anyway (e.g. due to a NULL pointer deref).

> +	/* -1 to map pin pair to gmbus index */
> +	return &dev_priv->gmbus[port - 1].adapter;
> +}
> +
>  void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed)
>  {
>  	struct intel_gmbus *bus = to_intel_gmbus(adapter);
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index c5c0973..4f92a11 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -837,8 +837,8 @@ static bool lvds_is_present_in_vbt(struct drm_device *dev,
>  		    child->device_type != DEVICE_TYPE_LFP)
>  			continue;
>  
> -		if (child->i2c_pin)
> -		    *i2c_pin = child->i2c_pin;
> +		if (intel_gmbus_is_port_valid(child->i2c_pin))
> +			*i2c_pin = child->i2c_pin;
>  
>  		/* However, we cannot trust the BIOS writers to populate
>  		 * the VBT correctly.  Since LVDS requires additional
> @@ -979,7 +979,8 @@ bool intel_lvds_init(struct drm_device *dev)
>  	 * preferred mode is the right one.
>  	 */
>  	intel_lvds->edid = drm_get_edid(connector,
> -					&dev_priv->gmbus[pin].adapter);
> +					intel_gmbus_get_adapter(dev_priv,
> +								pin));
>  	if (intel_lvds->edid) {
>  		if (drm_add_edid_modes(connector,
>  				       intel_lvds->edid)) {
> diff --git a/drivers/gpu/drm/i915/intel_modes.c b/drivers/gpu/drm/i915/intel_modes.c
> index 2978a3f..cc682a0 100644
> --- a/drivers/gpu/drm/i915/intel_modes.c
> +++ b/drivers/gpu/drm/i915/intel_modes.c
> @@ -55,7 +55,8 @@ bool intel_ddc_probe(struct intel_encoder *intel_encoder, int ddc_bus)
>  		}
>  	};
>  
> -	return i2c_transfer(&dev_priv->gmbus[ddc_bus].adapter, msgs, 2) == 2;
> +	return i2c_transfer(intel_gmbus_get_adapter(dev_priv, ddc_bus),
> +			    msgs, 2) == 2;
>  }
>  
>  /**
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> index 70fb275..830c8b5 100644
> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> @@ -1254,7 +1254,8 @@ intel_sdvo_get_analog_edid(struct drm_connector *connector)
>  	struct drm_i915_private *dev_priv = connector->dev->dev_private;
>  
>  	return drm_get_edid(connector,
> -			    &dev_priv->gmbus[dev_priv->crt_ddc_pin].adapter);
> +			    intel_gmbus_get_adapter(dev_priv,
> +						    dev_priv->crt_ddc_pin));
>  }
>  
>  enum drm_connector_status
> @@ -1922,12 +1923,12 @@ intel_sdvo_select_i2c_bus(struct drm_i915_private *dev_priv,
>  	if (mapping->initialized)
>  		pin = mapping->i2c_pin;
>  
> -	if (pin < GMBUS_NUM_PORTS) {
> -		sdvo->i2c = &dev_priv->gmbus[pin].adapter;
> +	if (intel_gmbus_is_port_valid(pin)) {
> +		sdvo->i2c = intel_gmbus_get_adapter(dev_priv, pin);
>  		intel_gmbus_set_speed(sdvo->i2c, GMBUS_RATE_1MHZ);
>  		intel_gmbus_force_bit(sdvo->i2c, true);
>  	} else {
> -		sdvo->i2c = &dev_priv->gmbus[GMBUS_PORT_DPB].adapter;
> +		sdvo->i2c = intel_gmbus_get_adapter(dev_priv, GMBUS_PORT_DPB);
>  	}
>  }
>  
> -- 
> 1.7.7.3
> 

-- 
Daniel Vetter
Mail: daniel@ffwll.ch
Mobile: +41 (0)79 365 57 48