linux-kernel - Re: [PATCH v2 5/6] tpm: add driver for cr50 on SPI

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Message-ID: <20190802204318.5aktcn7xnvzcwvqj@linux.intel.com>
Date:   Fri, 2 Aug 2019 23:43:18 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Alexander Steffen <Alexander.Steffen@...ineon.com>
Cc:     Stephen Boyd <swboyd@...omium.org>,
        Peter Huewe <peterhuewe@....de>,
        Andrey Pronin <apronin@...omium.org>,
        linux-kernel@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-integrity@...r.kernel.org,
        Duncan Laurie <dlaurie@...omium.org>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH v2 5/6] tpm: add driver for cr50 on SPI

On Thu, Jul 18, 2019 at 06:47:14PM +0200, Alexander Steffen wrote:
> On 17.07.2019 21:57, Stephen Boyd wrote:
> > Quoting Alexander Steffen (2019-07-17 05:00:06)
> > > On 17.07.2019 00:45, Stephen Boyd wrote:
> > > > From: Andrey Pronin <apronin@...omium.org>
> > > > 
> > > > +static unsigned short rng_quality = 1022;
> > > > +module_param(rng_quality, ushort, 0644);
> > > > +MODULE_PARM_DESC(rng_quality,
> > > > +              "Estimation of true entropy, in bits per 1024 bits.");
> > > 
> > > What is the purpose of this parameter? None of the other TPM drivers
> > > have it.
> > 
> > I think the idea is to let users override the quality if they decide
> > that they don't want to use the default value specified in the driver.
> 
> But isn't this something that applies to all TPMs, not only cr50? So
> shouldn't this parameter be added to one of the global modules (tpm?
> tpm_tis_core?) instead? Or do all low-level drivers (tpm_tis, tpm_tis_spi,
> ...) need this parameter to provide a consistent interface for the user?

This definitely something that is out of context of the patch set and
thus must be removed from the patch set.

/Jarkko