gpiostream: Stream.Duration() bug

[simokawa]

If I understand correctly, Stream.Resolution() is duration for a single bit and Duration() should return for all bits*.
Current implementation uses the count of bytes instead of bits, this looks wrong to me.
https://github.com/google/periph/blob/master/conn/gpio/gpiostream/gpiostream.go#L68
It should be
return b.Res * time.Duration(len(b.Bits)) * 8
Yeah, it is confusing that len(b.Bits) returns number of bytes.

There may be some code assuming this bug.

[maruel]

Yep :(

[simokawa]

Assuming number of bits to be 8*len(b.Bit) may work for most cases but we may want to specify number of bits explicitly in the struct. For example, gpiostream.Program{} could be a loop of 3bit-stream.

[maruel]

Ported to periph/conn#34.