[RFC PATCH 7/7] drm/i915: add DisplayPort CEC-Tunneling-over-AUX support

[Daniel Vetter]

On Thu, May 25, 2017 at 05:06:26PM +0200, Hans Verkuil wrote:
> From: Hans Verkuil <hans.verkuil at cisco.com>
> 
> Implement support for this DisplayPort feature.
> 
> The cec device is created whenever it detects an adapter that
> has this feature. It is only removed when a new adapter is connected
> that does not support this. If a new adapter is connected that has
> different properties than the previous one, then the old cec device is
> unregistered and a new one is registered to replace the old one.
> 
> Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>

Some small comments below.

> ---
>  drivers/gpu/drm/i915/Kconfig    | 11 ++++++++++
>  drivers/gpu/drm/i915/intel_dp.c | 46 +++++++++++++++++++++++++++++++++++++----
>  2 files changed, 53 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
> index a5cd5dacf055..f317b13a1409 100644
> --- a/drivers/gpu/drm/i915/Kconfig
> +++ b/drivers/gpu/drm/i915/Kconfig
> @@ -124,6 +124,17 @@ config DRM_I915_GVT_KVMGT
>  	  Choose this option if you want to enable KVMGT support for
>  	  Intel GVT-g.
>  
> +config DRM_I915_DP_CEC
> +	tristate "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support"
> +	depends on DRM_I915 && CEC_CORE
> +	select DRM_DP_CEC
> +	help
> +	  Choose this option if you want to enable HDMI CEC support for
> +	  DisplayPort/USB-C to HDMI adapters.
> +
> +	  Note: not all adapters support this feature, and even for those
> +	  that do support this often do not hook up the CEC pin.

Why Kconfig? There's not anything else optional in i915.ko (except debug
stuff ofc), since generally just not worth the pain. Also doesn't seem to
be wired up at all :-)

> +
>  menu "drm/i915 Debugging"
>  depends on DRM_I915
>  depends on EXPERT
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index ee77b519835c..38e17ee2548d 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -32,6 +32,7 @@
>  #include <linux/notifier.h>
>  #include <linux/reboot.h>
>  #include <asm/byteorder.h>
> +#include <media/cec.h>
>  #include <drm/drmP.h>
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_crtc.h>
> @@ -1405,6 +1406,7 @@ static void intel_aux_reg_init(struct intel_dp *intel_dp)
>  static void
>  intel_dp_aux_fini(struct intel_dp *intel_dp)
>  {
> +	cec_unregister_adapter(intel_dp->aux.cec_adap);
>  	kfree(intel_dp->aux.name);
>  }
>  
> @@ -4179,6 +4181,33 @@ intel_dp_check_mst_status(struct intel_dp *intel_dp)
>  	return -EINVAL;
>  }
>  
> +static bool
> +intel_dp_check_cec_status(struct intel_dp *intel_dp)
> +{
> +	bool handled = false;
> +
> +	for (;;) {
> +		u8 cec_irq;
> +		int ret;
> +
> +		ret = drm_dp_dpcd_readb(&intel_dp->aux,
> +					DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1,
> +					&cec_irq);
> +		if (ret < 0 || !(cec_irq & DP_CEC_IRQ))
> +			return handled;
> +
> +		cec_irq &= ~DP_CEC_IRQ;
> +		drm_dp_cec_irq(&intel_dp->aux);
> +		handled = true;
> +
> +		ret = drm_dp_dpcd_writeb(&intel_dp->aux,
> +					 DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1,
> +					 cec_irq);
> +		if (ret < 0)
> +			return handled;
> +	}
> +}

Shouldn't the above be a helper in the cec library? Doesn't look i915
specific to me at least ...

> +
>  static void
>  intel_dp_retrain_link(struct intel_dp *intel_dp)
>  {
> @@ -4553,6 +4582,7 @@ intel_dp_set_edid(struct intel_dp *intel_dp)
>  		intel_dp->has_audio = intel_dp->force_audio == HDMI_AUDIO_ON;
>  	else
>  		intel_dp->has_audio = drm_detect_monitor_audio(edid);
> +	cec_s_phys_addr_from_edid(intel_dp->aux.cec_adap, edid);
>  }
>  
>  static void
> @@ -4562,6 +4592,7 @@ intel_dp_unset_edid(struct intel_dp *intel_dp)
>  
>  	kfree(intel_connector->detect_edid);
>  	intel_connector->detect_edid = NULL;
> +	cec_phys_addr_invalidate(intel_dp->aux.cec_adap);
>  
>  	intel_dp->has_audio = false;
>  }
> @@ -4582,13 +4613,17 @@ intel_dp_long_pulse(struct intel_connector *intel_connector)
>  	intel_display_power_get(to_i915(dev), intel_dp->aux_power_domain);
>  
>  	/* Can't disconnect eDP, but you can close the lid... */
> -	if (is_edp(intel_dp))
> +	if (is_edp(intel_dp)) {
>  		status = edp_detect(intel_dp);
> -	else if (intel_digital_port_connected(to_i915(dev),
> -					      dp_to_dig_port(intel_dp)))
> +	} else if (intel_digital_port_connected(to_i915(dev),
> +						dp_to_dig_port(intel_dp))) {
>  		status = intel_dp_detect_dpcd(intel_dp);
> -	else
> +		if (status == connector_status_connected)
> +			drm_dp_cec_configure_adapter(&intel_dp->aux,
> +				     intel_dp->aux.name, dev->dev);

Did you look into also wiring this up for dp mst chains?
-Daniel

> +	} else {
>  		status = connector_status_disconnected;
> +	}
>  
>  	if (status == connector_status_disconnected) {
>  		memset(&intel_dp->compliance, 0, sizeof(intel_dp->compliance));
> @@ -5080,6 +5115,9 @@ intel_dp_hpd_pulse(struct intel_digital_port *intel_dig_port, bool long_hpd)
>  
>  	intel_display_power_get(dev_priv, intel_dp->aux_power_domain);
>  
> +	if (intel_dp->aux.cec_adap)
> +		intel_dp_check_cec_status(intel_dp);
> +
>  	if (intel_dp->is_mst) {
>  		if (intel_dp_check_mst_status(intel_dp) == -EINVAL) {
>  			/*
> -- 
> 2.11.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch