Change in coreboot[master]: drivers/i2c/tpm: Work around missing firmware_version in Ti50 < 0.0.15

[Reka Norman (Code Review)]

Attention is currently required from: Jes Klinke, Tim Wawrzynczak, Christian Walter, Julius Werner, Jett Rink.
Reka Norman has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/64202 )

Change subject: drivers/i2c/tpm: Work around missing firmware_version in Ti50 < 0.0.15
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Patch Set 6:

(1 comment)

Patchset:

PS2:
> It's not so much about the version number being guaranteed correct, more just that there is some num […]

If we add more calls to cr50_get_firmware_version() in the future, then presumably it would be because the calling code wants to handle different Ti50 versions differently. In that case, wouldn't silently returning a version which might be completely wrong just be likely to cause problems? I would argue that we do want cr50_get_firmware_version() to fail in this case.

I see your point about encapsulating this inside cr50_get_firmware_version() though. How about returning early from cr50_get_firmware_version() with CB_ERR and printing a log saying the firmware version is unimplemented. That will make sure if more calls are added in the future we'll notice this, and we can figure out how to handle the fact that the firmware version might be unimplemented on a case by case basis.