Re: [PATCH 1/1] Fix TPM chip hanging system before suspend/shutdown

["Jarkko Sakkinen" <jarkko@kernel.org>]

On Thu Mar 7, 2024 at 2:03 AM EET, Adam Alves wrote:
> My PC would hang on almost every shutdown/suspend until I started
> testing this patch and so far in the past week I haven’t experienced
> any problems anymore.
>
> I suspect that the root cause on my specific board is that after the
> ACPI command to put the device to S3 or S5, some firmware
> application/driver will try to use the TPM chip expecting it to be in
> Locality 0 as expected by TCG PC Client Platform Firmware Profile
> Version 1.06 Revision 52 (3.1.1 – Pre-OS Environment) and then when it
> fails to do so it simply halts the whole system.
>
> This issue might be related to the following bug:
> https://bugzilla.kernel.org/show_bug.cgi?id=217890
>
> Enable a user to configure the kernel
> through “tpm.locality_on_suspend=1” boot parameter so that the locality
> is set before suspend/shutdown in order to diagnose whether or not the
> board is one of the buggy ones that require this workaround. Since this
> bug is related to the board/platform instead of the specific TPM chip,
> call dmi_check_system on the tpm_init function so that this setting is
> automatically enabled for boards specified in code (ASUS TUF GAMING
> B460M-PLUS already included) – automatic configuration only works in
> case CONFIG_DMI is set though, since dmi_check_system is a non-op when
> CONFIG_DMI is not set.
>
> In case “tpm.locality_on_suspend=0” (the default) don't change any
> behavior thus preserving current functionality of any other board
> except ASUSTeK COMPUTER INC. TUF GAMING B460M-PLUS and possibly future
> boards as we successfully diagnose other boards with the same issue
> fixed by using “tpm.locality_on_suspend=1”.
>
> Signed-off-by: Adam Alves <adamoa@gmail.com>
> ---
>  drivers/char/tpm/tpm-chip.c      |  9 ++++++++
>  drivers/char/tpm/tpm-interface.c | 36 +++++++++++++++++++++++++++++++-
>  drivers/char/tpm/tpm.h           |  1 +
>  include/linux/tpm.h              |  1 +
>  4 files changed, 46 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index 42b1062e33cd..8fdf7a137a94 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -139,6 +139,9 @@ void tpm_chip_stop(struct tpm_chip *chip)
>  {
>  	tpm_go_idle(chip);
>  	tpm_relinquish_locality(chip);
> +	// If locality is to be preserved, we need to make sure it is Locality 0.

If you put that kind C++ comment you should also check out
https://www.kernel.org/doc/html/latest/process/coding-style.html

Other stuff that I said in my earlier response still applies.

BR, Jarkko