linux-kernel - Re: [Xen-devel] [PATCH] xen: use PCI interfaces to request IO and MEM resources on platform device.

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Date:	Tue, 11 Jan 2011 12:48:21 +0000
From:	"Jan Beulich" <JBeulich@...ell.com>
To:	"Ian Campbell" <ian.campbell@...rix.com>
Cc:	<Stefano.Stabellini@...citrix.com>, <jeremy@...p.org>,
	<xen-devel@...ts.xensource.com>, <konrad.wilk@...cle.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen: use PCI interfaces to request IO
	 and MEM resources on platform device.

>>> On 11.01.11 at 12:50, Ian Campbell <ian.campbell@...rix.com> wrote:
> This is the correct interface to use and something has broken the use
> of the previous incorrect interface (which fails because the request
> conflicts with the resources assigned for the PCI device itself
> instead of nesting like the PCI interfaces do).

While I agree that using the PCI interface is preferable, I can't see
how this can make a functional difference: __pci_request_region()
calls request_region() for the port resource and
__request_mem_region() for the mmio one exactly like what was
open coded before (request_mem_region() being equivalent to
__request_mem_region(..., 0), so I don't follow how this fixes
anything but half of the potentially incorrect use of "long" for
mmio_addr.

I'm mainly asking because if it really addresses some problem,
then unmodified_drivers/linux-2.6/platform-pci/platform-pci.c
in -unstable should probably get updated too.

Jan

> Signed-off-by: Ian Campbell <ian.campbell@...rix.com>
> Cc: stable@...nel.org # 2.6.37 only
> ---
>  drivers/xen/platform-pci.c |   21 +++++++--------------
>  1 files changed, 7 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/xen/platform-pci.c b/drivers/xen/platform-pci.c
> index c01b5dd..afbe041 100644
> --- a/drivers/xen/platform-pci.c
> +++ b/drivers/xen/platform-pci.c
> @@ -105,7 +105,7 @@ static int __devinit platform_pci_init(struct pci_dev 
> *pdev,
>  				       const struct pci_device_id *ent)
>  {
>  	int i, ret;
> -	long ioaddr, iolen;
> +	long ioaddr;
>  	long mmio_addr, mmio_len;
>  	unsigned int max_nr_gframes;
>  
> @@ -114,7 +114,6 @@ static int __devinit platform_pci_init(struct pci_dev 
> *pdev,
>  		return i;
>  
>  	ioaddr = pci_resource_start(pdev, 0);
> -	iolen = pci_resource_len(pdev, 0);
>  
>  	mmio_addr = pci_resource_start(pdev, 1);
>  	mmio_len = pci_resource_len(pdev, 1);
> @@ -125,19 +124,13 @@ static int __devinit platform_pci_init(struct pci_dev 
> *pdev,
>  		goto pci_out;
>  	}
>  
> -	if (request_mem_region(mmio_addr, mmio_len, DRV_NAME) == NULL) {
> -		dev_err(&pdev->dev, "MEM I/O resource 0x%lx @ 0x%lx busy\n",
> -		       mmio_addr, mmio_len);
> -		ret = -EBUSY;
> +	ret = pci_request_region(pdev, 1, DRV_NAME);
> +	if (ret < 0)
>  		goto pci_out;
> -	}
>  
> -	if (request_region(ioaddr, iolen, DRV_NAME) == NULL) {
> -		dev_err(&pdev->dev, "I/O resource 0x%lx @ 0x%lx busy\n",
> -		       iolen, ioaddr);
> -		ret = -EBUSY;
> +	ret = pci_request_region(pdev, 0, DRV_NAME);
> +	if (ret < 0)
>  		goto mem_out;
> -	}
>  
>  	platform_mmio = mmio_addr;
>  	platform_mmiolen = mmio_len;
> @@ -169,9 +162,9 @@ static int __devinit platform_pci_init(struct pci_dev 
> *pdev,
>  	return 0;
>  
>  out:
> -	release_region(ioaddr, iolen);
> +	pci_release_region(pdev, 0);
>  mem_out:
> -	release_mem_region(mmio_addr, mmio_len);
> +	pci_release_region(pdev, 1);
>  pci_out:
>  	pci_disable_device(pdev);
>  	return ret;




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