FW: [PATCH 4.4-rc8] pci: Make 4K config space available for non PCI-e/PCI-X devices

FW: [PATCH 4.4-rc8] pci: Make 4K config space available for non PCI-e/PCI-X devices

[Ananth, Rajesh]

Resending this in PLAIN TEXT.

Description:

The Kernel PCI driver that probes the devices always reports the config space as 256 bytes for the PCI devices that are not PCI-e or PCI-X.  
There are some vendor devices that are not PCI-e or PCI-X, but might have the configuration space data that is more than 256 bytes  in size to
be made accessible through the standard sys-fs "/sys/bus/pci/devices/./config" link.  

Currently, the current Kernel does not provide the extended config space access for those devices, and a proprietary mechanism is
oftentimes used by the vendor utilities to address that. As the problem could be seen, use of proprietary tools and utilities automatically
leads to user confusion of using non-standard tools across different vendor devices.

Patch:

--- linux-4.4-rc8/drivers/pci/probe.c.orig      2016-01-07 13:30:54.310392700 -0800
+++ linux-4.4-rc8/drivers/pci/probe.c   2016-01-07 13:32:14.586392700 -0800
@@ -1119,28 +1119,8 @@ static int pci_cfg_space_size_ext(struct

int pci_cfg_space_size(struct pci_dev *dev)
{
-       int pos;
-       u32 status;
-       u16 class;
-
-       class = dev->class >> 8;
-       if (class == PCI_CLASS_BRIDGE_HOST)
-               return pci_cfg_space_size_ext(dev);
-
-       if (!pci_is_pcie(dev)) {
-               pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
-               if (!pos)
-                       goto fail;
-
-               pci_read_config_dword(dev, pos + PCI_X_STATUS, &status);
-               if (!(status & (PCI_X_STATUS_266MHZ | PCI_X_STATUS_533MHZ)))
-                       goto fail;
-       }
-
        return pci_cfg_space_size_ext(dev);

- fail:
-       return PCI_CFG_SPACE_SIZE;
}

#define LEGACY_IO_RESOURCE     (IORESOURCE_IO | IORESOURCE_PCI_FIXED)


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    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
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    by me, under the same open source license (unless I am
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    Signed-off-by: Rajesh A Developer <rajesh.ananth@smartm.com>

Re: FW: [PATCH 4.4-rc8] pci: Make 4K config space available for non PCI-e/PCI-X devices

[Alex Williamson]

On Thu, 2016-01-07 at 23:20 +0000, Ananth, Rajesh wrote:
> Resending this in PLAIN TEXT.
> 
> Description:
> 
> The Kernel PCI driver that probes the devices always reports the
> config space as 256 bytes for the PCI devices that are not PCI-e or
> PCI-X.  
> There are some vendor devices that are not PCI-e or PCI-X, but might
> have the configuration space data that is more than 256 bytes  in
> size to
> be made accessible through the standard sys-fs
> "/sys/bus/pci/devices/./config" link.  
> 
> Currently, the current Kernel does not provide the extended config
> space access for those devices, and a proprietary mechanism is
> oftentimes used by the vendor utilities to address that. As the
> problem could be seen, use of proprietary tools and utilities
> automatically
> leads to user confusion of using non-standard tools across different
> vendor devices.
> 
> Patch:
> 
> --- linux-4.4-rc8/drivers/pci/probe.c.orig      2016-01-07
> 13:30:54.310392700 -0800
> +++ linux-4.4-rc8/drivers/pci/probe.c   2016-01-07 13:32:14.586392700
> -0800
> @@ -1119,28 +1119,8 @@ static int pci_cfg_space_size_ext(struct
> 
> int pci_cfg_space_size(struct pci_dev *dev)
> {
> -       int pos;
> -       u32 status;
> -       u16 class;
> -
> -       class = dev->class >> 8;
> -       if (class == PCI_CLASS_BRIDGE_HOST)
> -               return pci_cfg_space_size_ext(dev);
> -
> -       if (!pci_is_pcie(dev)) {
> -               pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
> -               if (!pos)
> -                       goto fail;
> -
> -               pci_read_config_dword(dev, pos + PCI_X_STATUS,
> &status);
> -               if (!(status & (PCI_X_STATUS_266MHZ |
> PCI_X_STATUS_533MHZ)))
> -                       goto fail;
> -       }
> -
>         return pci_cfg_space_size_ext(dev);
> 
> - fail:
> -       return PCI_CFG_SPACE_SIZE;
> }

Just no.  Use quirks if there are specific devices which provide
extended config space in non-standard ways, don't impose this broken
behavior everywhere.  Thanks,

Alex