Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Date:   Thu, 7 Apr 2022 11:25:26 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Lino Sanfilippo <LinoSanfilippo@gmx.de>
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
Message-ID: <20220407142526.GW64706@ziepe.ca>
References: <20220407111849.5676-1-LinoSanfilippo@gmx.de>
 <20220407111849.5676-2-LinoSanfilippo@gmx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220407111849.5676-2-LinoSanfilippo@gmx.de>
Precedence: bulk

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