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

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Date:   Thu, 14 Nov 2019 12:56:29 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
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 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.

Jason