lkml.org 
[lkml]   [2000]   [Jan]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: when CONFIG_PCI is not defined
Hi Jeff,

> Would you mind reviewing pci.h to make sure that all necessary functions
> are exported when CONFIG_PCI is not defined?
>
> I think that some of the recent PCI additions were not available for the
> !CONFIG_PCI case. This is wrong IMHO because pci.h is specifically
> designed to provide support to drivers even when CONFIG_PCI is
> undefined. It leads to much cleaner driver code.

I'm not sure at all that this is the right way to go.

With the old PCI interface, you could use

struct pci_dev *dev = NULL;
while (dev = pci_find_dev(VENDOR, DEVICE, dev)) {
pci_enable_device(dev);
init_your_device(dev->resource[0].start);
}

and it magically went optimized away by the compiler if CONFIG_PCI wasn't
defined. With the new interface, it would look this way:

int my_probe(struct pci_dev *dev)
{
pci_enable_device(dev);
init_your_device(dev->resource[0].start);
return 0;
}

struct pci_device_id my_ids[] = { ... };

struct pci_driver my_driver {
...
id_table: my_ids,
probe: my_probe,
}

{ pci_register_driver(&my_driver);

in which case nothing gets optimized away when compiling without CONFIG_PCI
and you end up with the driver full of dead code. Therefore to be on the
clean side of the glass, you need #ifdef CONFIG_PCI anyway, so there isn't
much sense in providing pci_register_driver() stub for PCI-less cases.

Have a nice fortnight
--
Martin `MJ' Mares <mj@ucw.cz> http://atrey.karlin.mff.cuni.cz/~mj/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
"Anything is good and useful if it's made of chocolate."

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.rutgers.edu
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:56    [W:0.042 / U:0.392 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site