On a Chromebook I'm working on I noticed a big (~1 second) delay
during bootup where nothing was happening. Right around this big
delay there were messages about the TPM:
[ 2.311352] tpm_tis_spi spi0.0: TPM ready IRQ confirmed on attempt 2
[ 3.332790] tpm_tis_spi spi0.0: Cr50 firmware version: ...
I put a few printouts in and saw that tpm_tis_spi_init() (specifically
tpm_chip_register() in that function) was taking the lion's share of
this time, though ~115 ms of the time was in cr50_print_fw_version().
Let's make a one-line change to prefer async probe for tpm_tis_spi.
There's no reason we need to block other drivers from probing while we
load.
NOTES:
* It's possible that other hardware runs through the init sequence
faster than Cr50 and this isn't such a big problem for them.
However, even if they are faster they are still doing _some_
transfers over a SPI bus so this should benefit everyone even if to
a lesser extent.
* It's possible that there are extra delays in the code that could be
optimized out. I didn't dig since once I enabled async probe they
no longer impacted me.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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