[media] em28xx-audio: don't hardcode audio URB calculus
The current code hardcodes the number of audio URBs, the number
of packets per URB and the maximum URB size.
This is not a good idea, as it:
- wastes more bandwidth than necessary, by using a very
large number of packets;
- those constants are bound to an specific scenario, with
a bandwidth of 48 kHz;
- don't take the maximum endpoint size into account;
- with urb->interval = 1 on xHCI, those constraints cause a "funny"
setup: URBs with 64 packets inside, with only 24 bytes total. E. g.
a complete waste of space.
Change the code to do dynamic URB audio calculus and allocation.
For now, use the same constraints as used before this patch, to
avoid regressions.
A good scenario (tested) seems to use those defines, instead:
#define EM28XX_MAX_AUDIO_BUFS 8
#define EM28XX_MIN_AUDIO_PACKETS 2
But let's not do such change here, letting the optimization to
happen on latter patches, after more tests.
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
2 files changed