linux-kernel - Re: [PATCH v2] dcdbas: force SMI to happen when expected

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Message-ID: <CC13D7E3DE58AE4096779C4F1D272C8E27D8EFA445@AUSX7MCPS308.AMER.DELL.COM>
Date:	Tue, 1 Mar 2011 09:53:57 -0600
From:	<Douglas_Warzecha@...l.com>
To:	<stuart_hayes@...oo.com>, <linux-kernel@...r.kernel.org>
CC:	<Shyam_Iyer@...l.com>
Subject: Re: [PATCH v2] dcdbas: force SMI to happen when expected

On 02/24/2011 8:35 PM, Stuart Hayes wrote:
> This is a reworked version of a very similar patch I sent about three
> weeks ago... a flaw was pointed out with the original.  That patch
> didn't make it into the kernel, though, so I'm just sending this one as
> a new patch.
> 
> The dcdbas driver can do an I/O write to cause a SMI to occur.  The SMI
> handler looks at certain registers and memory locations, so the SMI
> needs to happen immediately.  On some systems I/O writes are posted,
> though, causing the SMI to happen well after the "outb" occurred, which
> causes random failures.  Following the "outb" with an "inb" forces the
> write to go through even if it is posted.
> 
> This patch is against the 2.6.37.1 kernel.
> 
> Signed-off-by: Stuart Hayes <stuart_hayes@...oo.com>
> ---
> 
> --- linux-2.6.37/drivers/firmware/dcdbas.c	2011-01-18
> 10:44:44.869882461 -0500
> +++ linux-2.6.37_test/drivers/firmware/dcdbas.c	2011-02-24
> 13:23:58.663771596 -0500
> @@ -268,8 +268,10 @@ int dcdbas_smi_request(struct smi_cmd *s
>  	}
> 
>  	/* generate SMI */
> +	/* inb to force posted write through and make SMI happen now */
>  	asm volatile (
> -		"outb %b0,%w1"
> +		"outb %b0,%w1\n"
> +		"inb %w1"
>  		: /* no output args */
>  		: "a" (smi_cmd->command_code),
>  		  "d" (smi_cmd->command_address),
> 

Acked-by: Doug Warzecha <douglas_warzecha@...l.com>

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