Enable The I2S MCLK

jonsmirl · Posted at 10/27/2015 04:56:57

The naming is incorrect in the device tree. Look at the reg = <>. The one with the higher address is named I2S0. It just appears to be named wrong. The eight channel I2S is what makes HDMI audio, 8-channel I2S is not accessible on the external pins.

The device tree names can be anything, they are just strings. So this is confusing to a human but the computer doesn't care. The computer does not understand this "i2s1: i2s1@10200000" except as a collection of unique strings. You could name it "blue:rabbit@hat" and the DTC won't care.

jonsmirl · Posted at 10/27/2015 05:06:00

A likely cause for MCLK turning off is that there is default code somewhere turning unused pins into input GPIOs to save power. I have not looked, but you probably need to write a clock driver for the MCLK pin and support it in PINCTRL. In the DTS IS1 would then depend on this MCLK. Which would trigger the clock driver to turn it on. Implementing the clock driver marks the pin as in-use and will block the default GPIO behavior. This is not a lot of code, maybe 30-40 lines.

jonsmirl · Posted at 10/27/2015 05:07:58

The I2S section is also missing support for enabling an external I2S clock.

jonsmirl · Posted at 11/5/2015 08:09:06

This is way better than most other Chinese SOCs.

Allwinner only has support because volunteers are doing it, Allwinner pays them nothing.