Messages in this thread Patch in this message | | | From | Douglas Anderson <> | Subject | [PATCH] tpm_tis_spi: Prefer async probe | Date | Fri, 19 Jun 2020 14:20:01 -0700 |
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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> ---
drivers/char/tpm/tpm_tis_spi_main.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/char/tpm/tpm_tis_spi_main.c b/drivers/char/tpm/tpm_tis_spi_main.c index d96755935529..422766445373 100644 --- a/drivers/char/tpm/tpm_tis_spi_main.c +++ b/drivers/char/tpm/tpm_tis_spi_main.c @@ -288,6 +288,7 @@ static struct spi_driver tpm_tis_spi_driver = { .pm = &tpm_tis_pm, .of_match_table = of_match_ptr(of_tis_spi_match), .acpi_match_table = ACPI_PTR(acpi_tis_spi_match), + .probe_type = PROBE_PREFER_ASYNCHRONOUS, }, .probe = tpm_tis_spi_driver_probe, .remove = tpm_tis_spi_remove, -- 2.27.0.111.gc72c7da667-goog
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