linux-kernel - Re: [PATCH] ipmi:ssif: Fix double probe from tryacpi and trydmi

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Date:   Wed, 7 Mar 2018 07:34:17 -0600
From:   Corey Minyard <minyard@....org>
To:     Jiandi An <anjiandi@...eaurora.org>, arnd@...db.de,
        gregkh@...uxfoundation.org
Cc:     openipmi-developer@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ipmi:ssif: Fix double probe from tryacpi and trydmi

On 03/06/2018 11:49 PM, Jiandi An wrote:
> IPMI SSIF driver's parameter tryacpi and trydmi both
> are set to true.  The addition of IPMI DMI driver to
> create platform device for each IPMI device causes
> SSIF probe to be done twice on the same SMB I2C address
> for BMC.  Fix is to not call trydmi if tryacpi is able
> to find I2C address for BMC from SPMI ACPI table and
> probe successfully.

Why are you trying to do this?  Is something bad happening?

SPMI is not the preferred mechanism for detecting a device,
the preferred mechanism should be the acpi match table or
OF, followed by DMI, followed by SPMI.  In fact, it might be
best to just remove SPMI.

-corey

> Signed-off-by: Jiandi An <anjiandi@...eaurora.org>
> ---
>   drivers/char/ipmi/ipmi_ssif.c | 35 ++++++++++++++++++++++++-----------
>   1 file changed, 24 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/char/ipmi/ipmi_ssif.c b/drivers/char/ipmi/ipmi_ssif.c
> index 9d3b0fa..5c57363 100644
> --- a/drivers/char/ipmi/ipmi_ssif.c
> +++ b/drivers/char/ipmi/ipmi_ssif.c
> @@ -1981,29 +1981,41 @@ static int try_init_spmi(struct SPMITable *spmi)
>   	return new_ssif_client(myaddr, NULL, 0, 0, SI_SPMI, NULL);
>   }
>   
> -static void spmi_find_bmc(void)
> +static int spmi_find_bmc(void)
>   {
>   	acpi_status      status;
>   	struct SPMITable *spmi;
>   	int              i;
> +	int              rc = 0;
>   
>   	if (acpi_disabled)
> -		return;
> +		return -EPERM;
>   
>   	if (acpi_failure)
> -		return;
> +		return -ENODEV;
>   
>   	for (i = 0; ; i++) {
>   		status = acpi_get_table(ACPI_SIG_SPMI, i+1,
>   					(struct acpi_table_header **)&spmi);
> -		if (status != AE_OK)
> -			return;
> +		if (status != AE_OK) {
> +			if (i == 0)
> +				return -ENODEV;
> +			else
> +				return 0;
> +		}
>   
> -		try_init_spmi(spmi);
> +		rc = try_init_spmi(spmi);
> +		if (rc)
> +			return rc;
>   	}
> +
> +	return 0;
>   }
>   #else
> -static void spmi_find_bmc(void) { }
> +static int spmi_find_bmc(void)
> +{
> +	return -ENODEV;
> +}
>   #endif
>   
>   #ifdef CONFIG_DMI
> @@ -2104,12 +2116,13 @@ static int init_ipmi_ssif(void)
>   			       addr[i]);
>   	}
>   
> -	if (ssif_tryacpi)
> +	if (ssif_tryacpi) {
>   		ssif_i2c_driver.driver.acpi_match_table	=
>   			ACPI_PTR(ssif_acpi_match);
> -
> -	if (ssif_tryacpi)
> -		spmi_find_bmc();
> +		rv = spmi_find_bmc();
> +		if (!rv)
> +			ssif_trydmi = false;
> +	}
>   
>   	if (ssif_trydmi) {
>   		rv = platform_driver_register(&ipmi_driver);