[IMX8MP] isp-imx HDR mode undocumented function IsiSensorGetCompressCurveIss

[jjiimmyy]

@joanxie 

What is the purpose of IsiSensorGetCompressCurveIss function in the isp-imx?

This function is not documented in the porting guide but seems be part of the ISP pipeline. 

From cam_sensor.cpp, regardless of HDR mode (STITCH or NATIVE), this function is still required but why?

Is this ISP tone mapping? Is this sensor specific or ISP specific implementation function? 

I know you are helping me to get the de-compand data for the sensor I am porting.

If this function's is required for my sensor (HDR NATIVE, 20 bits companed),

please also provide me the code changes needed. 

Thanks

[jjiimmyy]

attatched is the code from tracing isp-imx.

[joanxie]

I checked this from internal team, got the reply as below:

"I couldn't access community this morning, I request this from internal team, and got reply as below
"Unfortunately we have no document to explain this function right now. From my understanding, it seems that customer is confused about why OS08A20, which is not using native HDR, requires the implementation of this function. For those sensors which do not need compress curve, the get compress curve is used for getting de-gamma curve. "