Re: [PATCH v2 07/42] misc/mei/hdcp: Get & Put for mei cl_device

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

On Thursday 08 March 2018 06:40 PM, Winkler, Tomas wrote:
>> Interfaces to obtain and release the cl_device reference is developed.
>> Using these interfaces intel hdcp driver will get the reference to the mei
>> client devices, so that hdcp2.2 service calls can be routed to that client
>> device.
>>
>> During registration, call back function will be registered with mei_hdcp driver
>> so that when the client device is removed intel hdcp driver can be informed.
>>
>> At a time only one reference is allowed in this interfaces.
>>
>> v2:
>>    Rebased.
> Linux kernel already provide notification chain,  please use that.
Sensing a problem here. Publisher module (mei_hdcp) for the notifier 
chain is loaded later than the I915's hdcp init (subscriber to the module).
Events that we will be interested are enabled and disabled states of the 
mei_hdcp_device.

I will explore further. Thanks for the suggestion
> This is not needed and I'm not sure it will ever work.
I am not sure, why do you think like that. This might not be in good 
shape but this is completely functional.
This v2 series is tested for HDCP2.2 feature on drm-tip before publishing.

 From starting I was not comfortable with this handshaking part between 
I915 and mei_hdcp. Thanks for the suggestions.
I will work on them.

--Ram
>
> Tomas
>
>   
>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>> ---
>>   drivers/misc/mei/hdcp/mei_hdcp.c | 55
>> +++++++++++++++++++++++++++++++++++++++-
>>   drivers/misc/mei/hdcp/mei_hdcp.h |  9 +++++++
>>   include/linux/mei_hdcp.h         | 47 ++++++++++++++++++++++++++++++++++
>>   3 files changed, 110 insertions(+), 1 deletion(-)  create mode 100644
>> include/linux/mei_hdcp.h
>>
>> diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c
>> b/drivers/misc/mei/hdcp/mei_hdcp.c
>> index 25df7034cfb4..63f77800a6f7 100644
>> --- a/drivers/misc/mei/hdcp/mei_hdcp.c
>> +++ b/drivers/misc/mei/hdcp/mei_hdcp.c
>> @@ -55,18 +55,71 @@ static int mei_hdcp_probe(struct mei_cl_device
>> *cldev,
>>   	mei_cldev_set_drvdata(cldev, &mei_hdcp);
>>
>>   	ret = mei_cldev_enable(cldev);
>> -	if (ret < 0)
>> +	if (ret < 0) {
>>   		dev_err(&cldev->dev, "mei_cldev_enable Failed. %d\n", ret);
>> +		goto err;
>> +	}
>> +
>> +	if (mei_hdcp.notify_on_cldev_change)
>> +		mei_hdcp.notify_on_cldev_change(mei_hdcp.client, cldev);
>> +
>> +	return 0;
>> +err:
>> +	if (mei_hdcp.notify_on_cldev_change)
>> +		mei_hdcp.notify_on_cldev_change(mei_hdcp.client, NULL);
>>
>>   	return ret;
>>   }
>>
>>   static int mei_hdcp_remove(struct mei_cl_device *cldev)  {
>> +	struct mei_hdcp *mei_hdcp = mei_cldev_get_drvdata(cldev);
>> +
>> +	if (mei_hdcp->notify_on_cldev_change)
>> +		mei_hdcp->notify_on_cldev_change(mei_hdcp->client, NULL);
>> +
>>   	mei_cldev_disable(cldev);
>> +
>>   	return 0;
>>   }
>>
>> +int mei_hdcp_cldev_get_reference(void *client_data,
>> +				 struct mei_cl_device **cldev,
>> +				 void (*notify_change)(void *client,
>> +						       struct mei_cl_device
>> +						       *cldev))
>> +{
>> +	if (!notify_change || !client_data)
>> +		return -EINVAL;
>> +
>> +	if (mei_hdcp.ref_cnt)
>> +		return -EBUSY;
>> +
>> +	if (!mei_cldev_active_and_enabled(mei_hdcp.cldev)) {
>> +		if (!notify_change)
>> +			return -EAGAIN;
>> +	} else {
>> +		*cldev = mei_hdcp.cldev;
>> +	}
>> +
>> +	mei_hdcp.ref_cnt++;
>> +	mei_hdcp.client = client_data;
>> +	mei_hdcp.notify_on_cldev_change = notify_change;
>> +
>> +	return 0;
>> +}
>> +EXPORT_SYMBOL(mei_hdcp_cldev_get_reference);
>> +
>> +void mei_hdcp_cldev_put_reference(struct mei_cl_device *cldev) {
>> +	if (cldev == mei_hdcp.cldev) {
>> +		mei_hdcp.ref_cnt--;
>> +		mei_hdcp.client = NULL;
>> +		mei_hdcp.notify_on_cldev_change = NULL;
>> +	}
>> +}
>> +EXPORT_SYMBOL(mei_hdcp_cldev_put_reference);
>> +
>>   #define WIDI_HECI_CLIENT_GUID	UUID_LE(0xB638AB7E, 0x94E2,
>> 0x4EA2, 0xA5, \
>>   					0x52, 0xD1, 0xC5, 0x4B, \
>>   					0x62, 0x7F, 0x04)
>> diff --git a/drivers/misc/mei/hdcp/mei_hdcp.h
>> b/drivers/misc/mei/hdcp/mei_hdcp.h
>> index c06c0d767c4f..7d792b5ad703 100644
>> --- a/drivers/misc/mei/hdcp/mei_hdcp.h
>> +++ b/drivers/misc/mei/hdcp/mei_hdcp.h
>> @@ -27,6 +27,15 @@
>>
>>   struct mei_hdcp {
>>   	struct mei_cl_device *cldev;
>> +
>> +	/* Reference to the HDCP2.2 service consumer */
>> +	void *client;
>> +
>> +	/* Callback function for the consumer on cl_device state change */
>> +	void (*notify_on_cldev_change)(void *client,
>> +				      struct mei_cl_device *cldev);
>> +
>> +	int ref_cnt;
>>   };
>>
>>   #endif /* __MEI_HDCP_H__ */
>> diff --git a/include/linux/mei_hdcp.h b/include/linux/mei_hdcp.h new file
>> mode 100644 index 000000000000..774b26da0c26
>> --- /dev/null
>> +++ b/include/linux/mei_hdcp.h
>> @@ -0,0 +1,47 @@
>> +/*
>> + * Copyright (c) 2017 Intel Corporation
>> + *
>> + * Permission to use, copy, modify, distribute, and sell this software
>> +and its
>> + * documentation for any purpose is hereby granted without fee,
>> +provided that
>> + * the above copyright notice appear in all copies and that both that
>> +copyright
>> + * notice and this permission notice appear in supporting
>> +documentation, and
>> + * that the name of the copyright holders not be used in advertising or
>> + * publicity pertaining to distribution of the software without
>> +specific,
>> + * written prior permission.  The copyright holders make no
>> +representations
>> + * about the suitability of this software for any purpose.  It is
>> +provided "as
>> + * is" without express or implied warranty.
>> + *
>> + * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO
>> THIS
>> +SOFTWARE,
>> + * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
>> FITNESS, IN
>> +NO
>> + * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL,
>> +INDIRECT OR
>> + * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
>> FROM LOSS
>> +OF USE,
>> + * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
>> OR
>> +OTHER
>> + * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE
>> OR
>> +PERFORMANCE
>> + * OF THIS SOFTWARE.
>> + */
>> +
>> +#ifndef _LINUX_MEI_HDCP_H
>> +#define _LINUX_MEI_HDCP_H
>> +
>> +#ifdef CONFIG_INTEL_MEI_HDCP
>> +int mei_hdcp_cldev_get_reference(void *client_data,
>> +				 struct mei_cl_device **cldev,
>> +				 void (*notify_change)(void *client,
>> +						       struct mei_cl_device
>> +						       *cldev));
>> +void mei_hdcp_cldev_put_reference(struct mei_cl_device *cldev); #else
>> +static inline int mei_hdcp_cldev_get_reference(void *client_data,
>> +				 struct mei_cl_device **cldev,
>> +				 void (*notify_change)(void *client,
>> +						       struct mei_cl_device
>> +						       *cldev))
>> +{
>> +	return -ENODEV;
>> +}
>> +static inline
>> +void mei_hdcp_cldev_put_reference(struct mei_cl_device *cldev) {}
>> +#endif /* defined (CONFIG_INTEL_MEI_HDCP) */ #endif /* defined
>> +(_LINUX_MEI_HDCP_H) */
>> --
>> 2.7.4

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