Furquan Shaikh has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/47310 )
Change subject: mb/google/zork: Add finalize GPIO routine ......................................................................
Patch Set 3:
(1 comment)
https://review.coreboot.org/c/coreboot/+/47310/3/src/mainboard/google/zork/v... File src/mainboard/google/zork/variants/berknip/gpio.c:
https://review.coreboot.org/c/coreboot/+/47310/3/src/mainboard/google/zork/v... PS3, Line 65: need an extra delay here
There was glitch-protection resistor with a value that was too high and kept the signal from going l […]
I think the change should be self-sufficient without a need to go back to bug to understand it. It is also helpful when partners add similar support for their own devices or in the future a new board wants to do something similar. Not everyone might have access to the bug.
About the glitch-protection resistor preventing the signal from going low - my reading of the bug is that it is related to not clearing of SRAM for the fingerprint MCU. And it is only for older hardware which will never be shipped. Since this is only for security reasons and does not have any functional impact, I think we don't really need to add the additional delay in coreboot. It simplifies the code path and the sequencing i.e. setting of GPIO_32, GPIO_11 and the 3 ms delay can be added directly in variants/baseboard/gpio_baseboard_tremblye.c without having to do this in each variant supporting fingerprint.