Change in coreboot[master]: mb/google/dedede/var/sasuke: Configure I2C times for touchpad/audio
Attention is currently required from: shkim, SH Kim, Kyösti Mälkki, Edward Doan, Karthik Ramasubramanian. Furquan Shaikh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/51335 )
Change subject: mb/google/dedede/var/sasuke: Configure I2C times for touchpad/audio ......................................................................
Patch Set 1:
(1 comment)
File src/mainboard/google/dedede/variants/sasuke/overridetree.cb:
https://review.coreboot.org/c/coreboot/+/51335/comment/9563b937_aa899f92 PS1, Line 66: .scl_lcnt = 190,
I just referred to https://partnerissuetracker.corp.google. […]
Thanks for the background shkim. Can you please capture the rise/fall times using this board on a scope and configure that in the overridetree? These tuning parameters depend on the board layout and shouldn't really be copied around different boards even if they are based on the same reference.
Some background on the rise/fall time:
On all Intel platforms, we have to tune rise/fall times as per designware guidelines and configure them in coreboot. P.S. This is different than what I2C spec says since the controller has its own internal counters for when it drives low from high, etc. As per designware spec:
Rise time: 0V -> .7Vdd Fall time: .7Vdd -> 0V High time (CLK only): .7Vdd (rising) -> .7Vdd (falling)
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Furquan Shaikh (Code Review)