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Subject: Re: [PATCH v2 1/5] media: cec-notifier: Get notifier by device and
 connector name
To:     Sean Paul <seanpaul@chromium.org>
Cc:     airlied@linux.ie, hans.verkuil@cisco.com, lee.jones@linaro.org,
        olof@lixom.net, seanpaul@google.com, sadolfsson@google.com,
        felixe@google.com, bleung@google.com, darekm@google.com,
        marcheu@chromium.org, fparent@baylibre.com,
        dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org,
        intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <1526648704-16873-1-git-send-email-narmstrong@baylibre.com>
 <1526648704-16873-2-git-send-email-narmstrong@baylibre.com>
 <20180518154819.GL3373@art_vandelay>
From:   Neil Armstrong <narmstrong@baylibre.com>
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Date:   Mon, 21 May 2018 10:53:00 +0200
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Hi Sean,

On 18/05/2018 17:48, Sean Paul wrote:
> On Fri, May 18, 2018 at 03:05:00PM +0200, Neil Armstrong wrote:
>> In non device-tree world, we can need to get the notifier by the driver
>> name directly and eventually defer probe if not yet created.
>>
>> This patch adds a variant of the get function by using the device name
>> instead and will not create a notifier if not yet created.
>>
>> But the i915 driver exposes at least 2 HDMI connectors, this patch also
>> adds the possibility to add a connector name tied to the notifier device
>> to form a tuple and associate different CEC controllers for each HDMI
>> connectors.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
> 
> Hi Neil,
> Thanks for posting these!
> 
>> ---
>>  drivers/media/cec/cec-notifier.c | 11 ++++++++---
>>  include/media/cec-notifier.h     | 27 ++++++++++++++++++++++++---
>>  2 files changed, 32 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/media/cec/cec-notifier.c b/drivers/media/cec/cec-notifier.c
>> index 16dffa0..dd2078b 100644
>> --- a/drivers/media/cec/cec-notifier.c
>> +++ b/drivers/media/cec/cec-notifier.c
>> @@ -21,6 +21,7 @@ struct cec_notifier {
>>  	struct list_head head;
>>  	struct kref kref;
>>  	struct device *dev;
>> +	const char *conn;
>>  	struct cec_adapter *cec_adap;
>>  	void (*callback)(struct cec_adapter *adap, u16 pa);
>>  
>> @@ -30,13 +31,14 @@ struct cec_notifier {
>>  static LIST_HEAD(cec_notifiers);
>>  static DEFINE_MUTEX(cec_notifiers_lock);
>>  
>> -struct cec_notifier *cec_notifier_get(struct device *dev)
>> +struct cec_notifier *cec_notifier_get_conn(struct device *dev, const char *conn)
>>  {
>>  	struct cec_notifier *n;
>>  
>>  	mutex_lock(&cec_notifiers_lock);
>>  	list_for_each_entry(n, &cec_notifiers, head) {
>> -		if (n->dev == dev) {
>> +		if (n->dev == dev &&
>> +		    (!conn || !strcmp(n->conn, conn))) {
>>  			kref_get(&n->kref);
>>  			mutex_unlock(&cec_notifiers_lock);
>>  			return n;
>> @@ -46,6 +48,8 @@ struct cec_notifier *cec_notifier_get(struct device *dev)
>>  	if (!n)
>>  		goto unlock;
>>  	n->dev = dev;
>> +	if (conn)
>> +		n->conn = kstrdup(conn, GFP_KERNEL);
>>  	n->phys_addr = CEC_PHYS_ADDR_INVALID;
>>  	mutex_init(&n->lock);
>>  	kref_init(&n->kref);
>> @@ -54,7 +58,7 @@ struct cec_notifier *cec_notifier_get(struct device *dev)
>>  	mutex_unlock(&cec_notifiers_lock);
>>  	return n;
>>  }
>> -EXPORT_SYMBOL_GPL(cec_notifier_get);
>> +EXPORT_SYMBOL_GPL(cec_notifier_get_conn);
>>  
>>  static void cec_notifier_release(struct kref *kref)
>>  {
>> @@ -62,6 +66,7 @@ static void cec_notifier_release(struct kref *kref)
>>  		container_of(kref, struct cec_notifier, kref);
>>  
>>  	list_del(&n->head);
>> +	kfree(n->conn);
>>  	kfree(n);
>>  }
>>  
>> diff --git a/include/media/cec-notifier.h b/include/media/cec-notifier.h
>> index cf0add7..814eeef 100644
>> --- a/include/media/cec-notifier.h
>> +++ b/include/media/cec-notifier.h
>> @@ -20,8 +20,10 @@ struct cec_notifier;
>>  #if IS_REACHABLE(CONFIG_CEC_CORE) && IS_ENABLED(CONFIG_CEC_NOTIFIER)
>>  
>>  /**
>> - * cec_notifier_get - find or create a new cec_notifier for the given device.
>> + * cec_notifier_get_conn - find or create a new cec_notifier for the given
>> + * device and connector tuple.
>>   * @dev: device that sends the events.
>> + * @conn: the connector name from which the event occurs
> 
> Probably best to use "name" instead of connector, since it doesn't necessarily
> _have_ to be a connector name. So, cec_notifier_get_by_name(dev, name)

I don't have a stong opinion, but since the CEC is tied to a connector, it should
mention connector, maybe conn_name ?

> 
>>   *
>>   * If a notifier for device @dev already exists, then increase the refcount
>>   * and return that notifier.
>> @@ -31,7 +33,8 @@ struct cec_notifier;
>>   *
>>   * Return NULL if the memory could not be allocated.
>>   */
>> -struct cec_notifier *cec_notifier_get(struct device *dev);
>> +struct cec_notifier *cec_notifier_get_conn(struct device *dev,
>> +					   const char *conn);
>>  
>>  /**
>>   * cec_notifier_put - decrease refcount and delete when the refcount reaches 0.
>> @@ -85,7 +88,8 @@ void cec_register_cec_notifier(struct cec_adapter *adap,
>>  			       struct cec_notifier *notifier);
>>  
>>  #else
>> -static inline struct cec_notifier *cec_notifier_get(struct device *dev)
>> +static inline struct cec_notifier *cec_notifier_get_conn(struct device *dev,
>> +							 const char *conn)
>>  {
>>  	/* A non-NULL pointer is expected on success */
>>  	return (struct cec_notifier *)0xdeadfeed;
>> @@ -121,6 +125,23 @@ static inline void cec_register_cec_notifier(struct cec_adapter *adap,
>>  #endif
>>  
>>  /**
>> + * cec_notifier_get - find or create a new cec_notifier for the given device.
>> + * @dev: device that sends the events.
>> + *
>> + * If a notifier for device @dev already exists, then increase the refcount
>> + * and return that notifier.
>> + *
>> + * If it doesn't exist, then allocate a new notifier struct and return a
>> + * pointer to that new struct.
> 
> You might also want to cover the case where you have multiple named notifiers
> for the same device. It looks like it just grabs the first one?

Yes, the code grabs the first one if not precised, do you mean I'll need to add
a line to document the behaviour ?

> 
> Sean
> 
>> + *
>> + * Return NULL if the memory could not be allocated.
>> + */
>> +static inline struct cec_notifier *cec_notifier_get(struct device *dev)
>> +{
>> +	return cec_notifier_get_conn(dev, NULL);
>> +}
>> +
>> +/**
>>   * cec_notifier_phys_addr_invalidate() - set the physical address to INVALID
>>   *
>>   * @n: the CEC notifier
>> -- 
>> 2.7.4
>>
> 

Thanks,
Neil