Karthik Ramasubramanian has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/43175 )
Change subject: mb/google/dedede/var/boten: Update devicetree ......................................................................
Patch Set 9:
(1 comment)
https://review.coreboot.org/c/coreboot/+/43175/9/src/mainboard/google/dedede... File src/mainboard/google/dedede/variants/boten/overridetree.cb:
https://review.coreboot.org/c/coreboot/+/43175/9/src/mainboard/google/dedede... PS9, Line 108: register "generic.enable_delay_ms" = "12"
Do we have stop_gpio / report_en for this Goodix controller?
As per the GT7375P Programming guide,
1) Time between enable (AVDD) and reset needs to be >= 10 ms i.e. enable_delay_ms >= 10 ms 2) Time between reset and stop (Report_En) needs to be >= 10 ms i.e. reset_delay_ms >= 10 ms 3) Time between reset and HID (I2C transaction) needs to be >= 120 ms i.e. (reset_delay_ms + stop_delay_ms) >= 120 ms 4) Time between disabling stop and reset off needs to be >= 1 ms i.e. stop_off_delay_ms >= 1ms 5) Time between reset off and enable off needs to be >= 1ms i.e. reset_off_delay_ms >= 1ms.
Based on that two observations: a) Both reset_delay_ms and stop_delay_ms are incorporated into reset_delay_ms itself leaving no delay between Report Enable and I2C transaction. Not sure if it is fine. b) Missing configuration for stop_off_delay_ms.
But every other google board using the Goodix controller use the same configuration as here. It does not hurt to double-confirm with the Goodix team to avoid copy-paste error.