Re: [PATCH] tpm: tpm_tis: add settle delay after releasing locality

[Jarkko Sakkinen <jarkko@kernel.org>]

On Mon, Jun 15, 2026 at 05:48:43AM +0100, Daniel Golle wrote:
> tpm_tis_core_init() releases locality 0 then immediately reclaims it via
> tpm_chip_start(); some TPMs (e.g. Nuvoton NPCT, TPM 2.0) need a few ms
> before granting it again, so probe fails with -1. This back-to-back
> release/request was added with the locality claim around TPM_INT_ENABLE.
> 
> Wait for the chip to settle after releasing the locality. A delay of
> TPM_TIMEOUT (5 ms) in __tpm_tis_relinquish_locality() is reliable; values
> below 3 ms are not.
> 
> Fixes: 0ef333f5ba7f ("tpm: add request_locality before write TPM_INT_ENABLE")
> Cc: stable@vger.kernel.org
> Signed-off-by: Daniel Golle <daniel@makrotopia.org>
> ---
>  drivers/char/tpm/tpm_tis_core.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 21d79ad3b164..6b90ff50c78d 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -171,6 +171,8 @@ static int __tpm_tis_relinquish_locality(struct tpm_tis_data *priv, int l)
>  {
>  	tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
>  
> +	tpm_msleep(TPM_TIMEOUT);
> +
>  	return 0;
>  }
>  
> -- 
> 2.54.0
> 

I think this is totally fine.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko