linux-kernel - Re: [PATCH 1/1] tpm_tis: handle -EPROBE_DEFER in tpm_tis_plat

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Date:   Mon, 8 Feb 2021 02:41:04 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Dirk Gouders <dirk@...ders.net>
Cc:     Peter Huewe <peterhuewe@....de>, Jason Gunthorpe <jgg@...pe.ca>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] tpm_tis: handle -EPROBE_DEFER in tpm_tis_plat_probe()

On Fri, Feb 05, 2021 at 09:20:22PM +0100, Dirk Gouders wrote:
> tpm_tis does not consider -EPROBE_DEFER in tpm_tis_plat_probe().
> Instead, without notification it falls back to polling mode if
> platform_get_irq_optional() returns a negative value.
> 
> This could lead to different behavior depending on wether tpm_tis was
> compiled builtin or as a module; in the latter case
> platform_get_irq_optional() often if not always returns a valid IRQ
> number on the first attempt.
> 
> Harmonize builtin and module behavior by returning -EPROBE_DEFER,
> effectively putting the device on the deferred probe list for later
> probe attempts.
> 
> Signed-off-by: Dirk Gouders <dirk@...ders.net>

This would be best picked to James' patch set.

> ---
>  drivers/char/tpm/tpm_tis.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/char/tpm/tpm_tis.c b/drivers/char/tpm/tpm_tis.c
> index 4ed6e660273a..4cf863704aa1 100644
> --- a/drivers/char/tpm/tpm_tis.c
> +++ b/drivers/char/tpm/tpm_tis.c
> @@ -320,6 +320,9 @@ static int tpm_tis_plat_probe(struct platform_device *pdev)
>  
>  	tpm_info.irq = platform_get_irq_optional(pdev, 0);
>  	if (tpm_info.irq <= 0) {
> +                if (tpm_info.irq == -EPROBE_DEFER)
> +                        /* Enter deferred probe list and try again, later. */
> +                        return -EPROBE_DEFER;
>  		if (pdev != force_pdev)
>  			tpm_info.irq = -1;
>  		else
> -- 
> 2.26.2
> 
> 

/Jarkko