Re: [RFC][PATCH 1/4] PCI legacy I/O port free driver - Introduce pci_set_bar_mask*()

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Russell King wrote:
On Wed, Feb 15, 2006 at 03:03:56PM +0900, Kenji Kaneshige wrote:

Andrew Morton wrote:

Kenji Kaneshige <[email protected]> wrote:


This patch introduces a new interface pci_select_resource() for PCI
device drivers to tell kernel what resources they want to use.


It'd be nice if we didn't need to introduce any new API functions for this.
If we could just do:

struct pci_something pci_something_table[] = {
	...
	{
		...
		.dont_allocate_io_space = 1,
		...
	},
	...
};

within each driver which wants it.

But I can't think of a suitable per-device-id structure with which we can
do that :(



My another idea was to use pci quirks. In this approach, we don't
need to introduce any new API. But I gave up this idea because it
looked abuse of pci quirks.

Anyway, I try to think about new ideas we don't need to introduce
any new API.


What about pci_enable_device_bars() ?


Yes, it's one option (In fact, my first idea was using it),
though we need to move the following lines into
pci_enable_device_bars() from pci_enable_device().

       pci_fixup_device(pci_fixup_enable, dev);
       dev->is_enabled = 1;

Actually, IIRC, there are one or two existing drivers using it.
In addition to pci_enable_device_bars(), we can use
pci_request_region() for requesting each region instead of using
pci_request_regions().

The reason I didn't use this option was I thought we would need
bigger changes to drivers if we use pci_enable_devie_bars() and
pci_request_region(). For example, if we use pci_request_region()
for requesting the specific regions and if an error occurs
while doing that, we need to release only the regions we succeeded
in requesting. I think this is a little bit troublesome for driver
writers. In adition, though this is my personal opinion, only one
API to enable devices (e.g. pci_enable_device()) looks nice to me.
Anyway, I think it would be nice if we can solve the problem by
as small changes as possible to the existing drivers.
How do you think?

Thanks,
Kenji Kaneshige
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