linux-kernel - Re: [PATCH] tpm_tis: turn on TPM before calling tpm_get

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Date:   Fri, 15 Nov 2019 19:43:29 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...pe.ca>
Cc:     Jerry Snitselaar <jsnitsel@...hat.com>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        Peter Huewe <peterhuewe@....de>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        linux-stable@...r.kernel.org,
        Christian Bundy <christianbundy@...ction.io>
Subject: Re: [PATCH] tpm_tis: turn on TPM before calling tpm_get_timeouts

On Thu, Nov 14, 2019 at 12:56:29PM -0400, Jason Gunthorpe wrote:
> On Thu, Nov 14, 2019 at 06:55:06PM +0200, Jarkko Sakkinen wrote:
> > > Would it function with the timeout values set at the beginning of
> > > tpm_tis_core_init (max values)?
> > 
> > tpm_get_timeouts() should be replaced with:
> > 
> > if (tpm_chip_start()) {
> > 	dev_err(dev, "Could not get TPM timeouts and durations\n");
> > 	rc = -ENODEV;
> > 	goto out_err;
> > }
> > 
> > tpm_stop_chip(chip);
> > 
> > tpm_get_timeouts() is called by tpm_auto_startup(). Also the function
> > should be moved to tpm_chip.c and converted to a static function so
> > that it won't be called from random cal sites like above.
> 
> Careful, the design here was to allow a driver to do only
> get_timeouts, then additional setup work, then do auto_startup()
> 
> Forcing a driver to do auto_startup too early may not be good.

All drivers always do it anyway because all drivers always call
tpm_chip_register().

/Jarkko