Troubleshooting why dual tuner devices cannot be scanned all the way

Customer feedback: Dual tuner platform, using rt820, two independent control can be swept to the station, as long as a dozen into dual tuner mode, there will be one way to scan. After obtaining the platform, test it, as the customer said. Why. At the beginning, I had been skeptical about hardware problems. For example, I was disturbed when I was working both ways. But I cannot tell where the interference is. The hardware project cannot be found, so I will start with the driver to find the cause.

1. In master switch and slave mode, the demo 0-2 path cannot be scanned, and the switch still cannot be scanned;

2. In dual tuner mode, disconnect the IIC of demo 0x1, and click OK.
It is undoubtedly the effect of demo 0x1. As a result, I checked the driver step by step and found that the initialization of the demo 0x1 would lead to another fail. I found that the crystal oscillator settings caused the problem. So I checked the tuner spec and found that the two single crystal oscillator used by tuner. In this case, one tuner output CLK to the other to work normally, but the driver does not have enable clk_out. update drier and test OK.

 

This problem is not difficult, but the solution is very important. This simple problem takes two days. At first, logical reasoning felt like a HW problem and a SW problem. If there are enough devices to test, you can quickly find out where the problem occurs.