Re: [PATCH v5 11/40] drm/i915: Enable superior HDCP ver that is capable

[Sean Paul <seanpaul@chromium.org>]

On Wed, Jun 27, 2018 at 02:10:00PM +0530, Ramalingam C wrote:
> Considering that HDCP2.2 is more secure than HDCP1.4, When a setup
> supports HDCP2.2 and HDCP1.4, HDCP2.2 will be enabled.
> 
> v2:
>   Included few optimization suggestions [Chris Wilson]
>   Commit message is updated as per the rebased version.
> v3:
>   No changes.
> v4:
>   Extra comment added and Style issue fixed [Uma]
> v5:
>   Rebased as part of patch reordering.
>   Flag is added for tracking hdcp2.2 encryption status.
> 
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_drv.h  |  1 +
>  drivers/gpu/drm/i915/intel_hdcp.c | 90 +++++++++++++++++++++++++++++++++++----
>  2 files changed, 83 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 2eeb82b04953..7624388eecd5 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -414,6 +414,7 @@ struct intel_hdcp {
>  
>  	/* HDCP2.2 related definitions */
>  	bool hdcp2_supported;
> +	bool hdcp2_in_use;
>  
>  	/*
>  	 * Content Stream Type defined by content owner. TYPE0(0x0) content can
> diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
> index 32a1a3f39b65..b34e3b1587d6 100644
> --- a/drivers/gpu/drm/i915/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/intel_hdcp.c
> @@ -21,6 +21,60 @@
>  					 (enum hdcp_physical_port)(port))
>  
>  static int intel_hdcp2_init(struct intel_connector *connector);
> +static int _intel_hdcp2_enable(struct intel_connector *connector);
> +static int _intel_hdcp2_disable(struct intel_connector *connector);
> +static
> +int intel_hdcp_read_valid_bksv(struct intel_digital_port *intel_dig_port,
> +			       const struct intel_hdcp_shim *shim, u8 *bksv);
> +static
> +struct intel_digital_port *conn_to_dig_port(struct intel_connector *connector);

Please avoid forward declarations of static functions. Just place things
appropriately in the file.

> +
> +static bool panel_supports_hdcp(struct intel_connector *connector)
> +{
> +	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
> +	struct intel_hdcp *hdcp = &connector->hdcp;
> +	bool capable = false;
> +	u8 bksv[5];
> +
> +	if (hdcp->hdcp_shim) {

This function can only be called from
intel_hdcp_enable() -> intel_hdcp_capable() -> panel_supports_hdcp()

Both of those preceding functions check if hdcp_shim is NULL.

> +		if (hdcp->hdcp_shim->hdcp_capable) {
> +			hdcp->hdcp_shim->hdcp_capable(intel_dig_port, &capable);
> +		} else {
> +			if (!intel_hdcp_read_valid_bksv(intel_dig_port,
> +							hdcp->hdcp_shim, bksv))
> +				capable = true;
> +		}
> +	}
> +
> +	return capable;
> +}
> +
> +static inline
> +bool panel_supports_hdcp2(struct intel_connector *connector)
> +{
> +	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
> +	struct intel_hdcp *hdcp = &connector->hdcp;
> +	bool capable = false;
> +
> +	/* Check the panel's hdcp2.2 compliance if platform supports it. */
> +	if (hdcp->hdcp2_supported)
> +		hdcp->hdcp_shim->hdcp_2_2_capable(intel_dig_port, &capable);
> +
> +	return capable;
> +}
> +
> +/* Is HDCP1.4 capable on Platform and Panel */
> +static inline bool intel_hdcp_capable(struct intel_connector *connector)
> +{
> +	return (connector->hdcp.hdcp_shim && panel_supports_hdcp(connector));

As mentioned, the hdcp_shim check is already covered by the caller. The way
things are setup, the shim checks only need to exist at the entry points
(enable/disable/check_link).

> +}
> +
> +/* Is HDCP2.2 capable on Platform and Panel */
> +static inline bool intel_hdcp2_capable(struct intel_connector *connector)
> +{
> +	return (connector->hdcp.hdcp2_supported &&
> +		panel_supports_hdcp2(connector));
> +}

The panel_supports_* functions don't seem necessary, just do the work in the
intel_hdcp*_capable functions.

>  
>  static int intel_hdcp_poll_ksv_fifo(struct intel_digital_port *intel_dig_port,
>  				    const struct intel_hdcp_shim *shim)
> @@ -796,20 +850,27 @@ int intel_hdcp_init(struct intel_connector *connector,
>  int intel_hdcp_enable(struct intel_connector *connector)
>  {
>  	struct intel_hdcp *hdcp = &connector->hdcp;
> -	int ret;
> +	int ret = -EINVAL;
>  
>  	if (!hdcp->hdcp_shim)
>  		return -ENOENT;
>  
>  	mutex_lock(&hdcp->hdcp_mutex);
>  
> -	ret = _intel_hdcp_enable(connector);
> -	if (ret)
> -		goto out;
> +	/*
> +	 * Considering that HDCP2.2 is more secure than HDCP1.4, If the setup
> +	 * is capable of HDCP2.2, it is preferred to use HDCP2.2.
> +	 */
> +	if (intel_hdcp2_capable(connector))
> +		ret = _intel_hdcp2_enable(connector);
> +	else if (intel_hdcp_capable(connector))
> +		ret = _intel_hdcp_enable(connector);
> +
> +	if (!ret) {
> +		hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_ENABLED;
> +		schedule_work(&hdcp->hdcp_prop_work);
> +	}
>  
> -	hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_ENABLED;
> -	schedule_work(&hdcp->hdcp_prop_work);
> -out:
>  	mutex_unlock(&hdcp->hdcp_mutex);
>  	return ret;
>  }
> @@ -826,7 +887,10 @@ int intel_hdcp_disable(struct intel_connector *connector)
>  
>  	if (hdcp->hdcp_value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
>  		hdcp->hdcp_value = DRM_MODE_CONTENT_PROTECTION_UNDESIRED;
> -		ret = _intel_hdcp_disable(connector);
> +		if (hdcp->hdcp2_in_use)
> +			ret = _intel_hdcp2_disable(connector);
> +		else
> +			ret = _intel_hdcp_disable(connector);
>  	}
>  
>  	mutex_unlock(&hdcp->hdcp_mutex);
> @@ -928,6 +992,16 @@ int intel_hdcp_check_link(struct intel_connector *connector)
>  	return ret;
>  }
>  
> +static int _intel_hdcp2_enable(struct intel_connector *connector)
> +{
> +	return 0;
> +}
> +
> +static int _intel_hdcp2_disable(struct intel_connector *connector)
> +{
> +	return 0;
> +}

nit: It'd probably be better to introduce the stubs with an error message, since
as you have it, you'll be able to "enable" HDCP2 without doing anything.

Sean

> +
>  static int i915_hdcp_component_master_bind(struct device *dev)
>  {
>  	struct drm_i915_private *dev_priv = kdev_to_i915(dev);
> -- 
> 2.7.4
> 
> _______________________________________________
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> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Sean Paul, Software Engineer, Google / Chromium OS
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