Hi Wolfram?

? 2016/4/16 1:58, Wolfram Sang ??:

quoted

The default frequency rate of function clock is 50M Hz, it can match
F/S mode, but HS mode not. If use default rate 50M to get 1.7M
scl-frequency rate , we could not get accurately 1.7M frequecy rate.
The input-clk-rate is more higher, we get more accurately
scl-frequency rate,  as 200M is a suitable input-clk-rate.

If 200M was used for F/S mode, it would increase power consumption, so
add a option that could be configured from DT.

If I understand you correctly, couldn't you use clk_set_rate() depending
on the desired scl frequency which is already described in DT as
clock-frequency?

Yeap, the default input clock rate is too low for HS mode, and it 's 
flexible that
we get it from DT.