linux-kernel - Re: [PATCH 1/2] PCI/MSI: Introduce pci_msix_table

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Date:	Wed, 21 Jan 2009 13:30:15 +1100
From:	Michael Ellerman <michael@...erman.id.au>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>,
	Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Matthew Wilcox <willy@...ux.intel.com>
Subject: Re: [PATCH 1/2] PCI/MSI: Introduce pci_msix_table_size()

On Wed, 2009-01-21 at 01:18 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@...k.pl>
> 
> Introduce new function pci_msix_table_size() returning the size of
> the MSI-X table of given PCI device or 0 if the device doesn't
> support MSI-X.
> 
> Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> ---
>  drivers/pci/msi.c   |   24 +++++++++++++++++++-----
>  include/linux/pci.h |    5 +++++
>  2 files changed, 24 insertions(+), 5 deletions(-)
> 
> Index: linux-2.6/drivers/pci/msi.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/msi.c
> +++ linux-2.6/drivers/pci/msi.c
> @@ -670,6 +670,23 @@ static int msi_free_irqs(struct pci_dev*
>  }
>  
>  /**
> + * pci_msix_table_size - return the number of device's MSI-X table entries
> + * @dev: pointer to the pci_dev data structure of MSI-X device function
> + */
> +int pci_msix_table_size(struct pci_dev *dev)
> +{
> +	int pos;
> +	u16 control;
> +
> +	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
> +	if (!pos)
> +		return 0;
> +
> +	pci_read_config_word(dev, msi_control_reg(pos), &control);
> +	return multi_msix_capable(control);
> +}
> +
> +/**
>   * pci_enable_msix - configure device's MSI-X capability structure
>   * @dev: pointer to the pci_dev data structure of MSI-X device function
>   * @entries: pointer to an array of MSI-X entries
> @@ -686,9 +703,8 @@ static int msi_free_irqs(struct pci_dev*
>   **/
>  int pci_enable_msix(struct pci_dev* dev, struct msix_entry *entries, int nvec)
>  {
> -	int status, pos, nr_entries;
> +	int status, nr_entries;
>  	int i, j;
> -	u16 control;
>  
>  	if (!entries)
>   		return -EINVAL;
> @@ -697,9 +713,7 @@ int pci_enable_msix(struct pci_dev* dev,
>  	if (status)
>  		return status;
>  
> -	pos = pci_find_capability(dev, PCI_CAP_ID_MSIX);
> -	pci_read_config_word(dev, msi_control_reg(pos), &control);
> -	nr_entries = multi_msix_capable(control);
> +	nr_entries = pci_msix_table_size(dev);
>  	if (nvec > nr_entries)
>  		return -EINVAL;

I see similar code in msix_capability_init(), although it still needs
pos. Did you deliberately not replace that, or just miss it?

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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