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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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.