[media] em28xx-audio: fix the period size in bytes

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If the period size is wrong, userspace will assume a wrong delay
any may negociate an inadequate value.

The em28xx devices use 8 for URB interval, in microframes,
and the driver programs it to have 64 packets.

That means that the IRQ sampling period is 125 * 8 * 64,
with is equal to 64 ms.

So, that's the minimal latency with the current settings. It is
possible to program a lower latency, by using less than 64 packets,
but that increases the amount of bandwitdh used, and the number of
IRQ events per second.

In any case, in order to support it, the driver logic should be
changed to fill those parameters in realtime.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

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This commit is contained in:

Mauro Carvalho Chehab 2014-01-10 13:29:16 -03:00

parent 1b3fd2d342

commit 49677aef90

1 changed files with 15 additions and 3 deletions

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drivers/media/usb/em28xx/em28xx-audio.c

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