Re: [PATCH v8 06/35] drm/i915: Enable and Disable of HDCP2.2

["C, Ramalingam" <ramalingam.c@intel.com>]

On 12/6/2018 4:00 PM, Daniel Vetter wrote:
> On Tue, Nov 27, 2018 at 04:13:04PM +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.
>>
>> When HDCP2.2 enabling fails and HDCP1.4 is supported, HDCP1.4 is
>> enabled.
>>
>> This change implements a sequence of enabling and disabling of
>> HDCP2.2 authentication and HDCP2.2 port encryption.
> Patch series suggestion for next time around: First build out the helper
> functions, then time them into the big picture like here. Personally I
> think that makes it easier to understand, but it's kinda personal choice.

Tried that already. But bisecting will give warnings as "defined but 
unused functions"

Hence moved to this approach.

> I guess this here works too.
>
>> v2:
>>    Included few optimization suggestions [Chris Wilson]
>>    Commit message is updated as per the rebased version.
>>    intel_wait_for_register is used instead of wait_for. [Chris Wilson]
>> v3:
>>    No changes.
>> v4:
>>    Extra comment added and Style issue fixed [Uma]
>> v5:
>>    Rebased as part of patch reordering.
>>    HDCP2 encryption status is tracked.
>>    HW state check is moved into WARN_ON [Daniel]
>> v6:
>>    Redefined the mei service functions as per comp redesign.
>>    Merged patches related to hdcp2.2 enabling and disabling [Sean Paul].
>>    Required shim functionality is defined [Sean Paul]
>> v7:
>>    Return values are handles [Uma]
>>    Realigned the code.
>>    Check for comp_master is removed.
>> v8:
>>    HDCP2.2 is attempted only if mei interface is up.
>>    Adjust to the new interface
>>    Avoid bool usage in struct [Tomas]
>>
>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_drv.h  |   5 +
>>   drivers/gpu/drm/i915/intel_hdcp.c | 223 +++++++++++++++++++++++++++++++++++---
>>   2 files changed, 214 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index bde82f3ada85..3e9f21d23442 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -383,6 +383,10 @@ struct intel_hdcp_shim {
>>   
>>   	/* Detects the HDCP protocol(DP/HDMI) required on the port */
>>   	enum mei_hdcp_wired_protocol (*hdcp_protocol)(void);
>> +
>> +	/* Detects whether Panel is HDCP2.2 capable */
>> +	int (*hdcp_2_2_capable)(struct intel_digital_port *intel_dig_port,
>> +				bool *capable);
>>   };
>>   
>>   struct intel_hdcp {
>> @@ -396,6 +400,7 @@ struct intel_hdcp {
>>   	/* HDCP2.2 related definitions */
>>   	/* Flag indicates whether this connector supports HDCP2.2 or not. */
>>   	u8 hdcp2_supported;
>> +	u8 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 760780f1105c..c1bd1ccd47cd 100644
>> --- a/drivers/gpu/drm/i915/intel_hdcp.c
>> +++ b/drivers/gpu/drm/i915/intel_hdcp.c
>> @@ -79,6 +79,43 @@ bool intel_hdcp_capable(struct intel_connector *connector)
>>   	return capable;
>>   }
>>   
>> +/* At present whether mei_hdcp component is binded with i915 master component */
>> +static bool intel_hdcp2_mei_binded(struct intel_connector *connector)
>> +{
>> +	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>> +	struct i915_hdcp_component_master *comp = dev_priv->hdcp_comp;
>> +
>> +	mutex_lock(&comp->mutex);
>> +	if (!comp->ops || !comp->dev) {
>> +		mutex_unlock(&comp->mutex);
>> +		return false;
>> +	}
>> +	mutex_unlock(&comp->mutex);
>> +
>> +	return true;
>> +}
>> +
>> +/* Is HDCP2.2 capable on Platform and Sink */
>> +static bool intel_hdcp2_capable(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;
>> +
>> +	/* I915 support for HDCP2.2 */
>> +	if (!hdcp->hdcp2_supported)
>> +		return false;
>> +
>> +	/* MEI services for HDCP2.2 */
>> +	if (!intel_hdcp2_mei_binded(connector))
>> +		return false;
> Why do we still need this with component? Driver load should be stalled
> out until it's all there, that was kinda the entire point of component,
> so we don't have to recheck all the time whether hdcp2 is still there or
> not.

We discussed this in previous patches. Lets decide whether this approach 
is good enough or not.

--Ram

>
>> +
>> +	/* Sink's capability for HDCP2.2 */
>> +	hdcp->shim->hdcp_2_2_capable(intel_dig_port, &capable);
>> +
>> +	return capable;
>> +}
>> +
>>   static int intel_hdcp_poll_ksv_fifo(struct intel_digital_port *intel_dig_port,
>>   				    const struct intel_hdcp_shim *shim)
>>   {
>> @@ -1114,8 +1151,7 @@ int hdcp2_authenticate_port(struct intel_connector *connector)
>>   	return ret;
>>   }
>>   
>> -static __attribute__((unused))
>> -int hdcp2_close_mei_session(struct intel_connector *connector)
>> +static int hdcp2_close_mei_session(struct intel_connector *connector)
>>   {
>>   	struct mei_hdcp_data *data = &connector->hdcp.mei_data;
>>   	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>> @@ -1137,12 +1173,157 @@ int hdcp2_close_mei_session(struct intel_connector *connector)
>>   	return ret;
>>   }
>>   
>> -static __attribute__((unused))
>> -int hdcp2_deauthenticate_port(struct intel_connector *connector)
>> +static int hdcp2_deauthenticate_port(struct intel_connector *connector)
>>   {
>>   	return hdcp2_close_mei_session(connector);
>>   }
>>   
>> +static int hdcp2_authenticate_sink(struct intel_connector *connector)
>> +{
>> +	DRM_ERROR("Sink authentication is done in subsequent patches\n");
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static int hdcp2_enable_encryption(struct intel_connector *connector)
>> +{
>> +	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
>> +	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>> +	struct intel_hdcp *hdcp = &connector->hdcp;
>> +	enum port port = connector->encoder->port;
>> +	int ret;
>> +
>> +	WARN_ON(I915_READ(HDCP2_STATUS_DDI(port)) & LINK_ENCRYPTION_STATUS);
>> +
>> +	if (hdcp->shim->toggle_signalling) {
>> +		ret = hdcp->shim->toggle_signalling(intel_dig_port, true);
>> +		if (ret) {
>> +			DRM_ERROR("Failed to enable HDCP signalling. %d\n",
>> +				  ret);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	if (I915_READ(HDCP2_STATUS_DDI(port)) & LINK_AUTH_STATUS) {
>> +		/* Link is Authenticated. Now set for Encryption */
>> +		I915_WRITE(HDCP2_CTL_DDI(port),
>> +			   I915_READ(HDCP2_CTL_DDI(port)) |
>> +			   CTL_LINK_ENCRYPTION_REQ);
>> +	}
>> +
>> +	ret = intel_wait_for_register(dev_priv, HDCP2_STATUS_DDI(port),
>> +				      LINK_ENCRYPTION_STATUS,
>> +				      LINK_ENCRYPTION_STATUS,
>> +				      TIME_FOR_ENCRYPT_STATUS_CHANGE);
>> +
>> +	return ret;
>> +}
>> +
>> +static int hdcp2_disable_encryption(struct intel_connector *connector)
>> +{
>> +	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
>> +	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>> +	struct intel_hdcp *hdcp = &connector->hdcp;
>> +	enum port port = connector->encoder->port;
>> +	int ret;
>> +
>> +	WARN_ON(!(I915_READ(HDCP2_STATUS_DDI(port)) & LINK_ENCRYPTION_STATUS));
>> +
>> +	I915_WRITE(HDCP2_CTL_DDI(port),
>> +		   I915_READ(HDCP2_CTL_DDI(port)) & ~CTL_LINK_ENCRYPTION_REQ);
>> +
>> +	ret = intel_wait_for_register(dev_priv, HDCP2_STATUS_DDI(port),
>> +				      LINK_ENCRYPTION_STATUS, 0x0,
>> +				      TIME_FOR_ENCRYPT_STATUS_CHANGE);
>> +	if (ret == -ETIMEDOUT)
>> +		DRM_DEBUG_KMS("Disable Encryption Timedout");
>> +
>> +	if (hdcp->shim->toggle_signalling) {
>> +		ret = hdcp->shim->toggle_signalling(intel_dig_port, false);
>> +		if (ret) {
>> +			DRM_ERROR("Failed to disable HDCP signalling. %d\n",
>> +				  ret);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int hdcp2_authenticate_and_encrypt(struct intel_connector *connector)
>> +{
>> +	int ret, i, tries = 3;
>> +
>> +	for (i = 0; i < tries; i++) {
>> +		ret = hdcp2_authenticate_sink(connector);
>> +		if (!ret)
>> +			break;
>> +
>> +		/* Clearing the mei hdcp session */
>> +		DRM_DEBUG_KMS("HDCP2.2 Auth %d of %d Failed.(%d)\n",
>> +			      i + 1, tries, ret);
>> +		if (hdcp2_deauthenticate_port(connector) < 0)
>> +			DRM_DEBUG_KMS("Port deauth failed.\n");
>> +	}
>> +
>> +	if (i != tries) {
>> +		/*
>> +		 * Ensuring the required 200mSec min time interval between
>> +		 * Session Key Exchange and encryption.
>> +		 */
>> +		msleep(HDCP_2_2_DELAY_BEFORE_ENCRYPTION_EN);
>> +		ret = hdcp2_enable_encryption(connector);
>> +		if (ret < 0) {
>> +			DRM_DEBUG_KMS("Encryption Enable Failed.(%d)\n", ret);
>> +			if (hdcp2_deauthenticate_port(connector) < 0)
>> +				DRM_DEBUG_KMS("Port deauth failed.\n");
>> +		}
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int _intel_hdcp2_enable(struct intel_connector *connector)
>> +{
>> +	struct intel_hdcp *hdcp = &connector->hdcp;
>> +	int ret;
>> +
>> +	DRM_DEBUG_KMS("[%s:%d] HDCP2.2 is being enabled. Type: %d\n",
>> +		      connector->base.name, connector->base.base.id,
>> +		      hdcp->content_type);
>> +
>> +	ret = hdcp2_authenticate_and_encrypt(connector);
>> +	if (ret) {
>> +		DRM_DEBUG_KMS("HDCP2 Type%d  Enabling Failed. (%d)\n",
>> +			      hdcp->content_type, ret);
>> +		return ret;
>> +	}
>> +
>> +	DRM_DEBUG_KMS("[%s:%d] HDCP2.2 is enabled. Type %d\n",
>> +		      connector->base.name, connector->base.base.id,
>> +		      hdcp->content_type);
>> +
>> +	hdcp->hdcp2_in_use = true;
>> +	return 0;
>> +}
>> +
>> +static int _intel_hdcp2_disable(struct intel_connector *connector)
>> +{
>> +	int ret;
>> +
>> +	DRM_DEBUG_KMS("[%s:%d] HDCP2.2 is being Disabled\n",
>> +		      connector->base.name, connector->base.base.id);
>> +
>> +	ret = hdcp2_disable_encryption(connector);
>> +
>> +	if (hdcp2_deauthenticate_port(connector) < 0)
>> +		DRM_DEBUG_KMS("Port deauth failed.\n");
>> +
>> +	connector->hdcp.hdcp2_in_use = false;
>> +
>> +	return ret;
>> +}
>> +
>>   static int i915_hdcp_component_master_bind(struct device *dev)
>>   {
>>   	struct drm_i915_private *dev_priv = kdev_to_i915(dev);
>> @@ -1342,22 +1523,33 @@ void intel_hdcp_exit(struct drm_i915_private *dev_priv)
>>   int intel_hdcp_enable(struct intel_connector *connector)
>>   {
>>   	struct intel_hdcp *hdcp = &connector->hdcp;
>> -	int ret;
>> +	int ret = -EINVAL;
>>   
>>   	if (!hdcp->shim)
>>   		return -ENOENT;
>>   
>>   	mutex_lock(&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);
>> +
>> +	/* When HDCP2.2 fails, HDCP1.4 will be attempted */
>> +	if (ret && intel_hdcp_capable(connector)) {
>> +		ret = _intel_hdcp_enable(connector);
>> +		if (!ret)
>> +			schedule_delayed_work(&hdcp->check_work,
>> +					      DRM_HDCP_CHECK_PERIOD_MS);
>> +	}
>> +
>> +	if (!ret) {
>> +		hdcp->value = DRM_MODE_CONTENT_PROTECTION_ENABLED;
>> +		schedule_work(&hdcp->prop_work);
>> +	}
>>   
>> -	hdcp->value = DRM_MODE_CONTENT_PROTECTION_ENABLED;
>> -	schedule_work(&hdcp->prop_work);
>> -	schedule_delayed_work(&hdcp->check_work,
>> -			      DRM_HDCP_CHECK_PERIOD_MS);
>> -out:
>>   	mutex_unlock(&hdcp->mutex);
>>   	return ret;
>>   }
>> @@ -1374,7 +1566,10 @@ int intel_hdcp_disable(struct intel_connector *connector)
>>   
>>   	if (hdcp->value != DRM_MODE_CONTENT_PROTECTION_UNDESIRED) {
>>   		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);
> Looks reasonable. So one thing we could be doing is already internally
> have a DRM_MODE_CONTENT_PROTECTION_ENABLED_TYPE1 for hdcp2.But the uapi
> would only return _ENABLED to userspace. But for internal tracking this
> would avoid the need for the separate hdcp2_in_use variable.
>
> Probably good cleanup/prep patch for the type0/1 uapi extension, once we
> get there.
>
> Aside from the component intergration question seems all reasonable. But I
> didn't yet review the hdcp2 flow, will do that once it's more complete in
> later patches.
> -Daniel
>
>>   	}
>>   
>>   	mutex_unlock(&hdcp->mutex);
>> -- 
>> 2.7.4
>>
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