On Tue, Feb 16, 2016 at 10:27:20AM +0100, Takashi Iwai wrote:
On Tue, 16 Feb 2016 09:59:37 +0100,
Aren't they currently ports? seq_midi.c creates just one sequencer device per card number.
Look at cards with synth support, e.g. emu10k1 or OPL3/OPL4.
Or snd-virmidi.
Should I export the client_index parameter of snd_seq_create_kernel_client too?
Well, I'd rather ask what are the requirements -- in wide ranges.
The original requirement was just the ability to get the card name.
Yep. And it's the assumption of only rawmidi, I suppose. How would it differentiate from synth?
My users are using a few identical USB MIDI keyboards [or USB MIDI interfaces] and I need to recognize the devices even after reboot.
=> I want a stable, unique (composite) device ID for kernel sequencer clients+ports.
My current ID is: client name, sysfs-path and port number.
The sound card number allows to find the device in sysfs and determine the used USB port as stable identifier. I hope, that the registration order for the ports of one USB MIDI device [or sound card] will always be the same.
see my prototype: https://build.opensuse.org/package/view_file/home:e9925248:branches:openSUSE...
OPL3/4 + emuXXX synth register with a different name, so they should be distinct.
And, as mentioned, some cards provide indeed multiple clients. How do you identify which client is for what? So far, it's identified only from the name string and the type bits of each port. Isn't it enough? If not, what have to be provided?
This patch is about the card. If we really need a method to identify the device, we can still add it later -- this patch does not obstruct such an extension.
Sure, it won't conflict. But, the question is (back to square) whether it's enough.
If we know that we shall change the API again, it's better to consider the design well from the beginning. A short-living API version bump is the thing we should avoid as much as possible. It's nothing but a needless stress for maintainers :)
That said, I'm not particularly against the currently proposed change. My only concern is whether we need any further change in (near) future.
+1
I just ask myself, if the device index would provide any useful information.
I don't know, how to map it to a anything below the soundcard in sysfs. Is the device ID dymanic? [= Are they depending, if I first load the rawmidi module and then the synth module or the other way around].
Regards, Martin