On Fri, 25 Apr 2008, Takashi Iwai wrote:
> Hm, indeed it's more than a single value...
>
> For multiple anonymous data, we can use a data with a key like below:
>
> struct device_hint {
> char *key;
> void *data;
> struct list_head list;
> };
>
> and the controller driver assigns the data like
>
> controller_init()
> {
> ...
> controller.hint.key = "ucb1000-irq";
> controller.hint.data = whatever;
> list_add(&controller.hint. &ac97->device_hint_list);
> ...
> }
>
> and the device driver retrieves the data like
>
> device_init()
> {
> struct device_hint *hint;
> hint = device_hint_get(&ac97->device_hint_list, "ucb1000-irq");
> if (hint) {
> whatever = hint->data;
> ...
> }
> }
>
> where device_hint_get() is defined like
>
> struct device_hint *device_hint_get(struct device_hint *head,
> const char *key)
> {
> struct device_hint *hint;
> list_for_each_entry(hint, head, list)
> if (!strcmp(hint, key))
> return hint;
> return NULL;
> }
>
> Of course, we can cast via container_of() to a container type instead
> of using a void pointer there.
>
> This is obviously an overweight for a single use-case, but if we have
> more and more complex ones, maybe worth to consider.
Sure. I applied the simple 'void *device_private_data' patch, because
current usage request is really trivial. We can implement complex code to
handle data for multiple "extra" devices on AC97 bus later.
Jaroslav
-----
Jaroslav Kysela <perex@xxxxxxxx>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
