linux-kernel - Re: [PATCH 2/5]PCI: x86 MMCONFIG: add legacy pci conf functions

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Date:	Wed, 19 Dec 2007 15:06:15 -0800
From:	Greg KH <gregkh@...e.de>
To:	tcamuso@...hat.com
Cc:	linux-kernel@...r.kernel.org, linux-pci@...ey.karlin.mff.cuni.cz,
	prarit@...hat.com
Subject: Re: [PATCH 2/5]PCI: x86 MMCONFIG: add legacy pci conf functions

On Wed, Dec 19, 2007 at 05:17:56PM -0500, tcamuso@...hat.com wrote:
> commit 307e3aecde8060af3802590f8c5bffb5456fe22b
> Author: Tony Camuso <tony.camuso@...com>
> Date:   Wed Dec 19 15:38:31 2007 -0500
> 
>     Modifies arch/x86/pci/direct.c to add the Legacy PCI Config routines
>     that will be made available, even when MMCONFIG is the platform default
>     PCI Config access mechanism. It also provides logic for selecting the
>     correct Legacy PCI Config access mechanism and the corresponding boot log
>     messages.
>     
>     Signed-off-by: Tony Camuso tony.camuso@...com
> 
> diff --git a/arch/x86/pci/direct.c b/arch/x86/pci/direct.c
> index 431c9a5..4e78002 100644
> --- a/arch/x86/pci/direct.c
> +++ b/arch/x86/pci/direct.c
> @@ -175,6 +175,32 @@ static struct pci_raw_ops pci_direct_conf2 = {
>  	.write =	pci_conf2_write,
>  };
>  
> +/*
> + * Legacy PCI Config read and write routines for buses that can't use
> + * MMCONFIG accesses in systems where MMCONFIG is the default PCI config
> + * access mechanism.
> + */
> +static struct pci_raw_ops *pci_legacy_conf;
> +
> +static int pci_ops_legacy_read(struct pci_bus *bus, unsigned int devfn,
> +			      int where, int size, u32 *value)
> +{
> +	return pci_legacy_conf->read(0, bus->number, devfn, where,
> +				     size, value);
> +}
> +
> +static int pci_ops_legacy_write(struct pci_bus *bus, unsigned int devfn,
> +			       int where, int size, u32 value)
> +{
> +	return pci_legacy_conf->write(0, bus->number, devfn, where,
> +				      size, value);
> +}
> +
> +struct pci_ops pci_legacy_ops = {
> +	.read =		pci_ops_legacy_read,
> +	.write =	pci_ops_legacy_write,
> +};

This whole structure is never used in this patch, why add it now?

>  /*
>   * Before we decide to use direct hardware access mechanisms, we try to do some
> @@ -258,18 +284,28 @@ void __init pci_direct_init(int type)
>  {
>  	if (type == 0)
>  		return;
> -	printk(KERN_INFO "PCI: Using configuration type %d\n", type);
> -	if (type == 1)
> +	if (type == 1) {
>  		raw_pci_ops = &pci_direct_conf1;
> -	else
> +		pci_legacy_conf = &pci_direct_conf1;
> +	} else {
>  		raw_pci_ops = &pci_direct_conf2;
> +		pci_legacy_conf = &pci_direct_conf2;

Why have two pointers to the same thing?  What is pci_legacy_conf going
to be used for?  Why not just use raw_pci_ops?

thanks,

greg k-h
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