TPM_RDRESP_NEED_DELAY was introduced in 2018 in CB:25322 after
observing errors with SLB9635 by Infineon. It has been confirmed
also SLB9670 and SLB9672 require a fix or delay here.
Presumably, prior to CB:4388 SLB9635 did not have this problem,
as this particular TPM shipped with samsung/lumpy Chromebook since
2011. In CB:4388 the code changed from polling the status register
(+burst_count) using a 32bit read to separated 8bit reads.
So far, experiments on samsung/lumpy and SLB9635 indicate that
it would be sufficient to add a single tpm_read_status() call
to see TIS_STS_DATA_AVAILABLE as set at the time of evaluating
the loop exit condition.
Change-Id: If5c3e93c7946ebf8226f7bba47b38253f6920c61
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Co-authored-by: Bill XIE <persmule@hardenedlinux.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76315
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Bill XIE <persmule@hardenedlinux.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
71c8dac9ca