From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: peterhuewe@gmx.de, jarkko@kernel.org, robh+dt@kernel.org,
devicetree@vger.kernel.org, linux-integrity@vger.kernel.org,
linux-kernel@vger.kernel.org, stefanb@linux.ibm.com,
p.rosenberger@kunbus.com, lukas@wunner.de
Subject: Re: [PATCH 1/5] tpm: add functions to set and unset the tpm chips reset state
Date: Sun, 10 Apr 2022 11:03:01 +0200 [thread overview]
Message-ID: <caf9dc77-8d81-9f79-9c4b-4b9e4fdf5b92@gmx.de> (raw)
In-Reply-To: <20220407142526.GW64706@ziepe.ca>
Hi,
On 07.04.22 at 16:25, Jason Gunthorpe wrote:
> On Thu, Apr 07, 2022 at 01:18:45PM +0200, Lino Sanfilippo wrote:
>> Currently it is not possible to set the tpm chips reset state from within
>> the driver. This is problematic if the chip is still in reset after the
>> system comes up. This may e.g. happen if the reset line is pulled into
>> reset state by a pin configuration in the device tree.
>
> This kind of system is badly misdesigned.
>
> TPM PCRs fundementally cannot work if the TPM reset line is under
> software control.
>
> Jason
>
you may be right about the misdesign, but as a matter of fact
there are systems which have the TPMs reset line connected to a GPIO and not
the system reset. For those systems we should provide a way to let at least the
driver put the TPM out of reset (note that on those systems the TPM reset can
be triggered by software anyway by asserting/deasserting the GPIO line).
Regards,
Lino
next prev parent reply other threads:[~2022-04-10 9:03 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-07 11:18 [PATCH 0/5] Support TPM Reset GPIO Lino Sanfilippo
2022-04-07 11:18 ` [PATCH 1/5] tpm: add functions to set and unset the tpm chips reset state Lino Sanfilippo
2022-04-07 14:25 ` Jason Gunthorpe
2022-04-10 9:03 ` Lino Sanfilippo [this message]
2022-04-10 17:11 ` Lukas Wunner
2022-04-11 11:47 ` Jason Gunthorpe
2022-04-14 12:13 ` Jarkko Sakkinen
2022-04-07 11:18 ` [PATCH 2/5] dt-bindings: tpm: document reset gpio property Lino Sanfilippo
2022-04-07 11:18 ` [PATCH 3/5] tpm: tpm_tis: get optionally defined reset gpio Lino Sanfilippo
2022-04-07 11:18 ` [PATCH 4/5] tpm: tpm_tis: make functions available for external linkage Lino Sanfilippo
2022-04-07 11:18 ` [PATCH 5/5] tpm: tpm_tis_spi_slb_9670: implement set_reset and unset_reset functions Lino Sanfilippo
2022-04-10 17:18 ` Lukas Wunner
2022-04-10 19:44 ` Lino Sanfilippo
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