On Wed, Mar 27, 2024 at 7:44 AM Ilias Apalodimas <ilias.apalodi...@linaro.org> wrote: > > Hi Tim, > > On Thu, 21 Mar 2024 at 20:02, Tim Harvey <thar...@gateworks.com> wrote: > > > > Instead of displaying what looks like an error message if a > > gpio-reset dt prop is missing for a TPM dipslay a more > > informative message about resetting the TPM if the gpio is found: > > > > before: > > tpm_tis_spi_probe: missing reset GPIO > > > > after: > > tpm@0: performing 1ms reset on gpio@30210000:12 > > > > Note that the reset dt binding prop used in this driver is not > > dt-compliant; it does not exist in the Linux dt-bindings documentation > > and the reset is not done by the Linux driver. > > Probably for a good reason. You aren't supposed to be able to reset a > TPM without resetting the CPUI as well no?
Hi Ilias, Could you clarify what you know about TPM reset? We use the ATTPM20P [1] which states in the datasheet under the reset pin: "To be compliant with TCG requirements, this pin needs to be tied to system reset. TPM_Init is indicated by asserting this pin." Our boards have a resistor loading option which routes the TPM RST# to an SoC GPIO or alternately to a POR# (hardware power on reset provided by power supply and/or PMIC). Could you point me to where in the spec it explains what the TPM reset should be connected to? > That being said, printing that the TPM was reset is pointless imho. > OTOH the existing error message at least points out a potential > problem in the DT. > I'm not sure if you are NAK'ing this patch or asking me to change it. Displaying a 'missing GPIO' message is not helpful when there is no GPIO in the dt bindings to begin with. Best Regards, Tim [1] https://ww1.microchip.com/downloads/en/DeviceDoc/ATTPM20P-Trusted-Platform-Module-TPM-2.0-SPI-Interface-Summary-Data-Sheet-DS40002082A.pdf > Thanks > /Ilias > > > > Signed-off-by: Tim Harvey <thar...@gateworks.com> > > --- > > drivers/tpm/tpm2_tis_spi.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/tpm/tpm2_tis_spi.c b/drivers/tpm/tpm2_tis_spi.c > > index de9cf8f21e07..944540f7a711 100644 > > --- a/drivers/tpm/tpm2_tis_spi.c > > +++ b/drivers/tpm/tpm2_tis_spi.c > > @@ -237,14 +237,14 @@ static int tpm_tis_spi_probe(struct udevice *dev) > > /* legacy reset */ > > ret = gpio_request_by_name(dev, "gpio-reset", 0, > > &reset_gpio, > > GPIOD_IS_OUT); > > - if (ret) { > > - log(LOGC_NONE, LOGL_NOTICE, > > - "%s: missing reset GPIO\n", __func__); > > + if (ret) > > goto init; > > - } > > log(LOGC_NONE, LOGL_NOTICE, > > "%s: gpio-reset is deprecated\n", __func__); > > } > > + log(LOGC_NONE, LOGL_NOTICE, > > + "%s: performing 1ms reset on %s:%d\n", dev->name, > > + reset_gpio.dev->name, reset_gpio.offset); > > dm_gpio_set_value(&reset_gpio, 1); > > mdelay(1); > > dm_gpio_set_value(&reset_gpio, 0); > > -- > > 2.25.1 > >
