Re: [PATCH v2 2/4] drm/i915: Read Vprime thrice incase of mismatch

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

On Thursday 29 March 2018 08:08 PM, Sean Paul wrote:
> On Thu, Mar 29, 2018 at 07:39:06PM +0530, Ramalingam C wrote:
>> In case of V prime mismatch, DP HDCP spec mandates the re-read of
>> Vprime atleast twice.
>>
>> This patch needed for DP HDCP1.4 CTS Test: 1B-05.
>>
>> v2:
>>    Moved the V' validation into a function for retry. [Sean Paul]
>>
>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_hdcp.c | 113 +++++++++++++++++++++++---------------
>>   1 file changed, 70 insertions(+), 43 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
>> index 96b9025dc759..f77d956b2b18 100644
>> --- a/drivers/gpu/drm/i915/intel_hdcp.c
>> +++ b/drivers/gpu/drm/i915/intel_hdcp.c
>> @@ -142,53 +142,17 @@ bool intel_hdcp_is_ksv_valid(u8 *ksv)
>>   	return true;
>>   }
>>   
>> -/* Implements Part 2 of the HDCP authorization procedure */
>> -static
>> -int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
>> -			       const struct intel_hdcp_shim *shim)
>> +static inline
> Why inline?
Its a mistake. Will correct it. thanks
>
>> +int intel_hdcp_validate_v_prime(struct intel_digital_port *intel_dig_port,
>> +				const struct intel_hdcp_shim *shim,
>> +				u8 *ksv_fifo, u8 num_downstream, u8 *bstatus)
>>   {
>>   	struct drm_i915_private *dev_priv;
>>   	u32 vprime, sha_text, sha_leftovers, rep_ctl;
>> -	u8 bstatus[2], num_downstream, *ksv_fifo;
>>   	int ret, i, j, sha_idx;
>>   
>>   	dev_priv = intel_dig_port->base.base.dev->dev_private;
>>   
>> -	ret = intel_hdcp_poll_ksv_fifo(intel_dig_port, shim);
>> -	if (ret) {
>> -		DRM_ERROR("KSV list failed to become ready (%d)\n", ret);
>> -		return ret;
>> -	}
>> -
>> -	ret = shim->read_bstatus(intel_dig_port, bstatus);
>> -	if (ret)
>> -		return ret;
>> -
>> -	if (DRM_HDCP_MAX_DEVICE_EXCEEDED(bstatus[0]) ||
>> -	    DRM_HDCP_MAX_CASCADE_EXCEEDED(bstatus[1])) {
>> -		DRM_ERROR("Max Topology Limit Exceeded\n");
>> -		return -EPERM;
>> -	}
>> -
>> -	/*
>> -	 * When repeater reports 0 device count, HDCP1.4 spec allows disabling
>> -	 * the HDCP encryption. That implies that repeater can't have its own
>> -	 * display. As there is no consumption of encrypted content in the
>> -	 * repeater with 0 downstream devices, we are failing the
>> -	 * authentication.
>> -	 */
>> -	num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]);
>> -	if (num_downstream == 0)
>> -		return -EINVAL;
>> -
>> -	ksv_fifo = kzalloc(num_downstream * DRM_HDCP_KSV_LEN, GFP_KERNEL);
>> -	if (!ksv_fifo)
>> -		return -ENOMEM;
>> -
>> -	ret = shim->read_ksv_fifo(intel_dig_port, num_downstream, ksv_fifo);
>> -	if (ret)
>> -		return ret;
>> -
>>   	/* Process V' values from the receiver */
>>   	for (i = 0; i < DRM_HDCP_V_PRIME_NUM_PARTS; i++) {
>>   		ret = shim->read_v_prime_part(intel_dig_port, i, &vprime);
>> @@ -353,7 +317,7 @@ int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
>>   			return ret;
>>   		sha_idx += sizeof(sha_text);
>>   	} else {
>> -		DRM_ERROR("Invalid number of leftovers %d\n", sha_leftovers);
>> +		DRM_DEBUG("Invalid number of leftovers %d\n", sha_leftovers);
>>   		return -EINVAL;
>>   	}
>>   
>> @@ -381,14 +345,77 @@ int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
>>   	if (intel_wait_for_register(dev_priv, HDCP_REP_CTL,
>>   				    HDCP_SHA1_COMPLETE,
>>   				    HDCP_SHA1_COMPLETE, 1)) {
>> -		DRM_ERROR("Timed out waiting for SHA1 complete\n");
>> +		DRM_DEBUG("Timed out waiting for SHA1 complete\n");
>>   		return -ETIMEDOUT;
>>   	}
>>   	if (!(I915_READ(HDCP_REP_CTL) & HDCP_SHA1_V_MATCH)) {
>> -		DRM_ERROR("SHA-1 mismatch, HDCP failed\n");
>> +		DRM_DEBUG("SHA-1 mismatch, HDCP failed\n");
> I think the DEBUG should be DEBUG_KMS, consistent with the rest of the file?
Will make it uniform

--Ram
>
>>   		return -ENXIO;
>>   	}
>>   
>> +	return 0;
>> +}
>> +
>> +/* Implements Part 2 of the HDCP authorization procedure */
>> +static
>> +int intel_hdcp_auth_downstream(struct intel_digital_port *intel_dig_port,
>> +			       const struct intel_hdcp_shim *shim)
>> +{
>> +	u8 bstatus[2], num_downstream, *ksv_fifo;
>> +	int ret, i, tries = 3;
>> +
>> +	ret = intel_hdcp_poll_ksv_fifo(intel_dig_port, shim);
>> +	if (ret) {
>> +		DRM_ERROR("KSV list failed to become ready (%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = shim->read_bstatus(intel_dig_port, bstatus);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (DRM_HDCP_MAX_DEVICE_EXCEEDED(bstatus[0]) ||
>> +	    DRM_HDCP_MAX_CASCADE_EXCEEDED(bstatus[1])) {
>> +		DRM_ERROR("Max Topology Limit Exceeded\n");
>> +		return -EPERM;
>> +	}
>> +
>> +	/*
>> +	 * When repeater reports 0 device count, HDCP1.4 spec allows disabling
>> +	 * the HDCP encryption. That implies that repeater can't have its own
>> +	 * display. As there is no consumption of encrypted content in the
>> +	 * repeater with 0 downstream devices, we are failing the
>> +	 * authentication.
>> +	 */
>> +	num_downstream = DRM_HDCP_NUM_DOWNSTREAM(bstatus[0]);
>> +	if (num_downstream == 0)
>> +		return -EINVAL;
>> +
>> +	ksv_fifo = kzalloc(num_downstream * DRM_HDCP_KSV_LEN, GFP_KERNEL);
>> +	if (!ksv_fifo)
>> +		return -ENOMEM;
>> +
>> +	ret = shim->read_ksv_fifo(intel_dig_port, num_downstream, ksv_fifo);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/*
>> +	 * When V prime mismatches, DP Spec mandates re-read of
>> +	 * V prime atleast twice.
>> +	 */
>> +	for (i = 0; i < tries; i++) {
>> +		ret = intel_hdcp_validate_v_prime(intel_dig_port, shim,
>> +						  ksv_fifo, num_downstream,
>> +						  bstatus);
>> +		if (!ret)
>> +			break;
>> +	}
>> +
>> +	if (i == tries) {
>> +		DRM_ERROR("V Prime validation failed.(%d)\n", ret);
>> +		return ret;
>> +	}
>> +
>>   	DRM_DEBUG_KMS("HDCP is enabled (%d downstream devices)\n",
>>   		      num_downstream);
>>   	return 0;
>> -- 
>> 2.7.4
>>

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