On 11/15/16 21:41, Hans Verkuil wrote:
> Hi Philipp,
>
> On 11/15/2016 07:24 PM, Philipp Zabel wrote:
>> Hi Hans,
>>
>> Am Montag, den 14.11.2016, 16:22 +0100 schrieb Hans Verkuil:
>>> From: Hans Verkuil <hans.verkuil at cisco.com>
>>>
>>> Add support for HDMI hotplug and EDID notifiers, which is used to convey
>>> information from HDMI drivers to their CEC and audio counterparts.
>>>
>>> Based on an earlier version from Russell King:
>>>
>>> https://patchwork.kernel.org/patch/9277043/
>>>
>>> The hdmi_notifier is a reference counted object containing the HDMI state
>>> of an HDMI device.
>>>
>>> When a new notifier is registered the current state will be reported to
>>> that notifier at registration time.
>>>
>>> Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
>>> ---
>>> drivers/video/Kconfig | 3 +
>>> drivers/video/Makefile | 1 +
>>> drivers/video/hdmi-notifier.c | 136
>>> ++++++++++++++++++++++++++++++++++++++++++
>>> include/linux/hdmi-notifier.h | 43 +++++++++++++
>>> 4 files changed, 183 insertions(+)
>>> create mode 100644 drivers/video/hdmi-notifier.c
>>> create mode 100644 include/linux/hdmi-notifier.h
>>>
>>> diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
>>> index 3c20af9..1ee7b9f 100644
>>> --- a/drivers/video/Kconfig
>>> +++ b/drivers/video/Kconfig
>>> @@ -36,6 +36,9 @@ config VIDEOMODE_HELPERS
>>> config HDMI
>>> bool
>>>
>>> +config HDMI_NOTIFIERS
>>> + bool
>>> +
>>> if VT
>>> source "drivers/video/console/Kconfig"
>>> endif
>>> diff --git a/drivers/video/Makefile b/drivers/video/Makefile
>>> index 9ad3c17..65f5649 100644
>>> --- a/drivers/video/Makefile
>>> +++ b/drivers/video/Makefile
>>> @@ -1,5 +1,6 @@
>>> obj-$(CONFIG_VGASTATE) += vgastate.o
>>> obj-$(CONFIG_HDMI) += hdmi.o
>>> +obj-$(CONFIG_HDMI_NOTIFIERS) += hdmi-notifier.o
>>>
>>> obj-$(CONFIG_VT) += console/
>>> obj-$(CONFIG_LOGO) += logo/
>>> diff --git a/drivers/video/hdmi-notifier.c b/drivers/video/hdmi-notifier.c
>>> new file mode 100644
>>> index 0000000..c2a4f1b
>>> --- /dev/null
>>> +++ b/drivers/video/hdmi-notifier.c
>>> @@ -0,0 +1,136 @@
>>> +#include <linux/export.h>
>>> +#include <linux/hdmi-notifier.h>
>>> +#include <linux/string.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/list.h>
>>> +
>>> +struct hdmi_notifiers {
>>> + struct list_head head;
>>> + struct device *dev;
>>> + struct hdmi_notifier *n;
>>> +};
>>
>> This struct is not used, can be removed.
>
> Indeed.
>
>>
>>> +static LIST_HEAD(hdmi_notifiers);
>>> +static DEFINE_MUTEX(hdmi_notifiers_lock);
>>> +
>>> +struct hdmi_notifier *hdmi_notifier_get(struct device *dev)
>>> +{
>>> + struct hdmi_notifier *n;
>>> +
>>> + mutex_lock(&hdmi_notifiers_lock);
>>> + list_for_each_entry(n, &hdmi_notifiers, head) {
>>> + if (n->dev == dev) {
>>> + mutex_unlock(&hdmi_notifiers_lock);
>>> + kref_get(&n->kref);
>>> + return n;
>>> + }
>>> + }
>>> + n = kzalloc(sizeof(*n), GFP_KERNEL);
>>> + if (!n)
>>> + goto unlock;
>>> + mutex_init(&n->lock);
>>> + BLOCKING_INIT_NOTIFIER_HEAD(&n->notifiers);
>>> + kref_init(&n->kref);
>>
>> + n->dev = dev;
>>
>> Currently n->dev is never set, so every caller of this function gets its
>> own hdmi_notifier.
>
> Oops! Well, I did say it was compile-tested only :-)
>
>>
>>> + list_add_tail(&n->head, &hdmi_notifiers);
>>> +unlock:
>>> + mutex_unlock(&hdmi_notifiers_lock);
>>> + return n;
>>> +}
>>> +EXPORT_SYMBOL_GPL(hdmi_notifier_get);
>>> +
>>> +static void hdmi_notifier_release(struct kref *kref)
>>> +{
>>> + struct hdmi_notifier *n =
>>> + container_of(kref, struct hdmi_notifier, kref);
>>> +
I also forgot to remove this notifier from the global list.
I've updated my git branch to fix this.
Hans
