At Wed, 14 Jan 2009 15:14:54 +0000, James Courtier-Dutton wrote:
Takashi Iwai wrote:
At Mon, 12 Jan 2009 15:06:51 +0000, James Courtier-Dutton wrote:
2009/1/12 Takashi Iwai tiwai@suse.de:
At Mon, 12 Jan 2009 14:42:06 +0000, James Courtier-Dutton wrote:
Sounds good to me. One can keep the wrapper outside of the kernel, and only available in alsa-driver for those out of tree people.
Yes, that's good. I think it'd be better to do that after one kernel-cycle later for a softer landing, though.
How soft do we need this?
One kernel cycle is enough.
The change is probably max of 3 lines of code per sound card that has an out of tree driver. The only one I am aware of is the xfi one. With the wrapper being more than 3 lines of code being put into the kernel only to be removed again seems a little un-necessary to me. For internal kernel changes, I don't think we should care about out of kernel drivers. None of the rest of the kernel developers go out of their way for anything out-of-mainline.
Well, my main concern isn't about out-of-kernel drivers like xfi, but the drivers that will come from other trees. The codes outside ALSA tree, for example, V4L, can't be always controlled by us (suppose a new V4L driver comes in for the next kernel). And these are more or less "mainline" development.
If you see the linux-next development, you'll find how the internal API can be a pain among several tree merges. A typical API change (that has been often seen in driver-core area) introduces first a wrapper while converting all in the present kernel, then kill it at the next cycle.
Ah! I did not think of V4L. Once cycle seems OK to me. I hope it creates a warning message to the V4L developers, although, I don't see why you cannot include a patch to V4L together with all the other alsa cards drivers that would get into linux-next.
It's possible, but often not too easy if a new V4L driver is introduced in their tree. In that case, either we or they import their/out patch. This can be a mess once if the tree gets rebased or a similar thing happens.
Of course, I already patched the existing drivers (also found in usb gadget). But any upcoming stuff can be hard to expect...
thanks,
Takashi