From: Douglas Anderson <dianders@chromium.org>
To: Peter Huewe <peterhuewe@gmx.de>,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: Nicolas Boichat <drinkcat@chromium.org>,
Andrey Pronin <apronin@chromium.org>,
Stephen Boyd <swboyd@chromium.org>,
Douglas Anderson <dianders@chromium.org>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jason Gunthorpe <jgg@ziepe.ca>,
linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH] tpm_tis_spi: Prefer async probe
Date: Fri, 19 Jun 2020 14:20:01 -0700 [thread overview]
Message-ID: <20200619141958.1.I58d549fded1fd2299543ede6a103fe2bb94c805d@changeid> (raw)
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
next reply other threads:[~2020-06-19 21:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 21:20 Douglas Anderson [this message]
2020-06-22 14:56 ` [PATCH] tpm_tis_spi: Prefer async probe Doug Anderson
2020-06-23 1:36 ` Jarkko Sakkinen
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