I realize the delay should be moved to __tpm_tis_relinquish_locality. I'll change that in a v2 patch.
On Mon, May 18, 2026 at 11:09 PM Jim Broadus <[email protected]> wrote: > > Some TPMs fail to grant locality when requested immediately after being > relinquished. In this case, the TPM_ACCESS_REQUEST_USE bit of the > TPM_ACCESS register is cleared immediately without setting > TPM_ACCESS_ACTIVE_LOCALITY. > > This issue can be seen at boot since tpm_chip_start, called right > after locality is relinquished, fails. This causes the probe to fail: > > tpm_tis MSFT0101:00: probe with driver tpm_tis failed with error -1 > > This occurs on some older Dell Latitudes and maybe others. To work > around this, add a "settle" boolean param to tpm_tis. When this is > enabled, a delay is added after locality is relinquished. > > Signed-off-by: Jim Broadus <[email protected]> > --- > Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ > drivers/char/tpm/tpm_tis.c | 7 +++++++ > drivers/char/tpm/tpm_tis_core.c | 3 +++ > drivers/char/tpm/tpm_tis_core.h | 1 + > 4 files changed, 18 insertions(+) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index 4d0f545fb3ec..5b7111033fbb 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -7651,6 +7651,13 @@ Kernel parameters > defined by Trusted Computing Group (TCG) see > > https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/ > > + tpm_tis.settle= [HW,TPM] > + Format: <bool> > + When enabled, this adds a delay after locality is > + relinquished. Some TPMs will fail to grant locality if > + requested immediately after being relinquished. This > + causes the probe to fail. > + > tp_printk [FTRACE] > Have the tracepoints sent to printk as well as the > tracing ring buffer. This is useful for early boot up > diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c > index 9aa230a63616..8ac0ea78570e 100644 > --- a/drivers/char/tpm/tpm_tis.c > +++ b/drivers/char/tpm/tpm_tis.c > @@ -101,6 +101,10 @@ module_param(force, bool, 0444); > MODULE_PARM_DESC(force, "Force device probe rather than using ACPI entry"); > #endif > > +static bool settle; > +module_param(settle, bool, 0444); > +MODULE_PARM_DESC(settle, "Add settle time after relinquish"); > + > #if defined(CONFIG_PNP) && defined(CONFIG_ACPI) > static int has_hid(struct acpi_device *dev, const char *hid) > { > @@ -242,6 +246,9 @@ static int tpm_tis_init(struct device *dev, struct > tpm_info *tpm_info) > if (itpm || is_itpm(ACPI_COMPANION(dev))) > set_bit(TPM_TIS_ITPM_WORKAROUND, &phy->priv.flags); > > + if (settle) > + set_bit(TPM_TIS_SETTLE_AFTER_RELINQUISH, &phy->priv.flags); > + > return tpm_tis_core_init(dev, &phy->priv, irq, &tpm_tcg, > ACPI_HANDLE(dev)); > } > diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c > index 21d79ad3b164..68be26fa5817 100644 > --- a/drivers/char/tpm/tpm_tis_core.c > +++ b/drivers/char/tpm/tpm_tis_core.c > @@ -184,6 +184,9 @@ static int tpm_tis_relinquish_locality(struct tpm_chip > *chip, int l) > __tpm_tis_relinquish_locality(priv, l); > mutex_unlock(&priv->locality_count_mutex); > > + if (test_bit(TPM_TIS_SETTLE_AFTER_RELINQUISH, &priv->flags)) > + tpm_msleep(TPM_TIMEOUT); > + > return 0; > } > > diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h > index 6c3aa480396b..413cac5e0f31 100644 > --- a/drivers/char/tpm/tpm_tis_core.h > +++ b/drivers/char/tpm/tpm_tis_core.h > @@ -90,6 +90,7 @@ enum tpm_tis_flags { > TPM_TIS_DEFAULT_CANCELLATION = 2, > TPM_TIS_IRQ_TESTED = 3, > TPM_TIS_STATUS_VALID_RETRY = 4, > + TPM_TIS_SETTLE_AFTER_RELINQUISH = 5, > }; > > struct tpm_tis_data { > -- > 2.54.0 >
