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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>
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During flow control we are just reading from the TPM, yet our spi_xfer
has the tx_buf and rx_buf both non-NULL which means we're requesting a
full duplex transfer.
SPI is always somewhat of a full duplex protocol anyway and in theory
the other side shouldn't really be looking at what we're sending it
during flow control, but it's still a bit ugly to be sending some
"random" data when we shouldn't.
The default tpm_tis_spi_flow_control() tries to address this by
setting 'phy->iobuf[0] = 0'. This partially avoids the problem of
sending "random" data, but since our tx_buf and rx_buf both point to
the same place I believe there is the potential of us sending the
TPM's previous byte back to it if we hit the retry loop.
Another flow control implementation, cr50_spi_flow_control(), doesn't
address this at all.
Let's clean this up and just make the tx_buf NULL before we call
flow_control(). Not only does this ensure that we're not sending any
"random" bytes but it also possibly could make the SPI controller
behave in a slightly more optimal way.
NOTE: no actual observed problems are fixed by this patch--it's was
just made based on code inspection.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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In a recent change to the SPI subsystem [1], a new 'delay' struct was added
to replace the 'delay_usecs'. This change replaces the current
'delay_usecs' with 'delay' for this driver.
The 'spi_transfer_delay_exec()' function [in the SPI framework] makes sure
that both 'delay_usecs' & 'delay' are used (in this order to preserve
backwards compatibility).
[1] commit bebcfd272df6485 ("spi: introduce `delay` field for
`spi_transfer` + spi_transfer_delay_exec()")
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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Revert tpm_tis_spi_mod.ko back to tpm_tis_spi.ko as the rename could
break user space scripts. This can be achieved by renaming tpm_tis_spi.c
as tpm_tis_spi_main.c. Then tpm_tis_spi-y can be used inside the
makefile.
Cc: Andrey Pronin <apronin@chromium.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: stable@vger.kernel.org # 5.5.x
Fixes: 797c0113c9a4 ("tpm: tpm_tis_spi: Support cr50 devices")
Reported-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Tested-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
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