On Tue, May 1, 2012 at 7:28 AM, John Crispin [off-list ref] wrote:

On 30/04/12 19:54, David Daney wrote:

quoted

On 04/30/2012 10:46 AM, John Crispin wrote:

quoted

On MIPS we want to call of_irq_map_pci from inside

arch/mips/include/asm/pci.h:extern int pcibios_map_irq(
                const struct pci_dev *dev, u8 slot, u8 pin);

For this to work we need to change several functions to const usage.

I think there is a mismatch on this throughout the kernel.

Properly fixing it requires touching many more places than these.
Although I haven't tried it, I wouldn't be surprised if doing this
caused warnings to appear in non-MIPS code.

Ralf had a patch at one point that tried to make this consistent
tree-wide, but it is not yet applied.

David Daney

Hi,

Ok, lets see what Ralf has to say.

I just tested the patch on x86 with OF enabled and drivers turned on
that use the API. I did not see any errors appear.

I'm far from a const expert, but I think this should be safe.  Here's
my reasoning:

We're changing pci_swizzle_interrupt_pin() to take a pointer to a
constant struct pci_dev.  pci_swizzle_interrupt_pin() only reads the
struct pci_dev; it doesn't modify it.  It is legal to pass either
"struct pci_dev *" or "const struct pci_dev *" to a function expecting
"const struct pci_dev *"; the callee just won't be able to modify the
struct, even if the caller can.

Similar reasoning applies to of_irq_map_pci().

So I'm fine with this.  You sent it to Grant, so I'll assume he'll
merge it unless I hear otherwise.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>