linux-kernel - Re: [PATCH v3 1/4] tpm: Add a flag to indicate TPM power is managed by firmware

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Date:   Fri, 09 Aug 2019 21:02:01 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Stephen Boyd <swboyd@...omium.org>, Peter Huewe <peterhuewe@....de>
Cc:     linux-kernel@...r.kernel.org, linux-integrity@...r.kernel.org,
        Andrey Pronin <apronin@...omium.org>,
        Duncan Laurie <dlaurie@...omium.org>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <groeck@...omium.org>,
        Alexander Steffen <Alexander.Steffen@...ineon.com>
Subject: Re: [PATCH v3 1/4] tpm: Add a flag to indicate TPM power is
 managed by firmware

On Tue, 2019-08-06 at 15:07 -0700, Stephen Boyd wrote:
> On some platforms, the TPM power is managed by firmware and therefore we
> don't need to stop the TPM on suspend when going to a light version of
> suspend such as S0ix ("freeze" suspend state). Add a chip flag to
> indicate this so that certain platforms can probe for the usage of this
> light suspend and avoid touching the TPM state across suspend/resume.

The commit message should mention the new constant.

> +	if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED)
> +		if (!pm_suspend_via_firmware())

Why both checks are needed?

If both checks are needed, you could write it as a single
conditional statement:

if (chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED &&
    !pm_suspend_via_firmware())

/Jarkko