DRV8308: Register data isn't written by SPI.

Hi,

Our system could not write correctly as folloing stiuation.

【Questions】
1. Our system's tL(SCS) is approximately 0.3usec. It's meet your specification(tl(SCS) > 100ns).
　But sometimes our system could not write correctly.
　Refer to above figure of "Current situation".
　Is 300ns not enough time for tl(SCS)?
　If time is not enough, what is your recommended value?

2. When we set tL(SCS) to approximately 4.9msec, our system was able to write correctly.
　Refer to above figure of "After countermeasures".
　Is there a regulation for the time from data transfer completion to SCS going low?
　If you have regulation then please let me know the min value.