Furquan Shaikh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/39285 )
Change subject: mb/google/dedede Add Audio support for waddledoo ......................................................................
Patch Set 9:
(1 comment)
https://review.coreboot.org/c/coreboot/+/39285/8/src/mainboard/google/dedede... File src/mainboard/google/dedede/variants/waddledoo/overridetree.cb:
https://review.coreboot.org/c/coreboot/+/39285/8/src/mainboard/google/dedede... PS8, Line 41: .scl_lcnt = 176, : .scl_hcnt = 95, : .sda_hold = 36, These are dependent on board design and are from the perspective of the I2C controller. The designware controller guide provides details of how the values need to be calculated. This bug also has more details of how it was done on Reef: b/35582963. You can find similar bugs for other platforms too. I would recommend raising a bug to perform the same tuning for waddledoo and we can add these values in when the tuning is done.
Audio is verified working, but these parameters are not electrically verified.
Without proper tuning, you would see that the CLK frequency could be higher than 400kHz leading to issues talking to the device. There might not be errors observed all the time, so it is difficult to catch these unless you are running long stress tests. Easy way to check this is to monitor CLK frequency on the scope.