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| Who | What | When |
|---|---|---|
| hverkuil | neg: ping | [12:55] |
| .......... (idle for 45mn) | ||
| mchehab | hverkuil: at v4l2_find_nearest_format(), any reason why it is passing the frame size array via a struct argument instead of directly?
IMHO, instead of: const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(const struct v4l2_discrete_probe *probe, s32 width, s32 height); I would be doing: const struct v4l2_frmsize_discrete *v4l2_find_nearest_format(const struct v4l2_frmsize_discrete *sizes, const usize_t num_sizes, s32 width, s32 height); btw, this is currently used only on vivid drivers/media/platform/vivid/vivid-vid-cap.c: v4l2_find_nearest_format(&webcam_probe, mp->width, mp->height); | [13:40] |
| hverkuil | mchehab: feel free to modify it. It was added in 2.6.37, without any driver using it.
It seems vivid is the only driver that ever used it. I'm not emotionally attached to the code :-) | [13:44] |
| mchehab | :-)
ok, I'll modify it and document hopefully, after documented, other drivers might start using it... if not, well, we can just move the function to vivid | [13:46] |
| .............. (idle for 1h8mn) | ||
| *** | benjiG has left | [14:55] |
| .......................... (idle for 2h6mn) | ||
| mchehab | hverkuil: v4l2-event.rst mentions a "kevent struct"
but I was unable to find where such struct is wouldn't that be, instead, struct v4l2_subscribed_event? | [17:01] |
| hverkuil | that should be v4l2_kevent. In media/v4l2-events.h
Well, let me double check. | [17:02] |
| mchehab | ah, OK
v4l2_kevent is embedded at struct v4l2_subscribed_event | [17:02] |
| hverkuil | yes, v4l2_kevent. | [17:03] |
| mchehab | the header file mentions the latter
(v4l2_subscribed_event) while the framework doc says only kevent in other words, doc says: "When the user subscribes to an event the driver will allocate a number of kevent structs for that event. " while the header says: "The v4l2_subscribed_event struct is added to that list, one for every subscribed event." I suspect that the latter is correct | [17:03] |
| hverkuil | Both are correct. | [17:07] |
| mchehab | ok
I'll try to make it clearer mchehab is trying to merge both descriptions into one | [17:07] |
| hverkuil | When you subscribe to an event for a filehandle the kernel will allocate a v4l2_subscribed_event struct. At the end of that struct is an array of v4l2_kevent structs. The size of that array depends on the type of the event. When an event arrives it is queued in that array with some special handling rules when the array is full.
So when the doc says "When the user subscribes to an event the driver will allocate a number of kevent structs for that event. " it is referring to the v4l2_kevent arrays at the end of v4l2_subscribed_event. And when the header says: "The v4l2_subscribed_event struct is added to that list, one for every subscribed event." it refers to the fact that a v4l2_fh has a list of subscribed events... ... aka struct v4l2_subscribed_event, one struct each for every subscribed events. The documentation is wrong about the kevent name: s/kevent/v4l2_kevent/ And I'm sure the docs/header can be improved. I think this is fall-out from a major event rewrite that I did a few kernel versions after the event API was first introduced. v4l2_kevent was probably originally called just kevent. Basically (if I remember correctly) in the original code there was only a single event array which contained events for all subscribed events. So the events[] array at the end of struct v4l2_subscribed_event didn't exist. Instead v4l2_fh had a single events[] array used by all subscribed events. | [17:09] |
| neg | hverkuil: pong | [17:18] |
| hverkuil | neg: I mailed you my question. | [17:20] |
| neg | hverkuil: Ohh I will reply to your mail :-) | [17:21] |
| ..... (idle for 20mn) | ||
| mchehab | hverkuil: ok, I guess I figure out what's missing/incomplete there...
https://git.linuxtv.org/mchehab/experimental.git/commit/?h=v4l-docs&id=403379980206e0dab0b9e9cd900d2768d72c451a | [17:41] |
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