Platform device model drawback

[Grant Likely]

On 11/15/05, Greg KH <greg at kroah.com> wrote:
> On Tue, Nov 15, 2005 at 01:34:47PM -0600, Kumar Gala wrote:
> > This is where the confusion is.  We have two instances of device A.  We
> > want instance 1 of device A bound to driver "enet" and instance 2 of
> > device A bound to "serial".
>
> That's different from what was described earlier :)
>
> In this case, you need two different struct devices.
Which is what we have.

>
> > Today both instances are called "deviceA".  However we can't register two
> > different drivers as "deviceA".
>
> Nor would you want to.
>
> > Not sure if that clarifies the issue any.
>
> A bit.  I think it still sounds messy...
Does this help?  (We also discussed this a bit at the PPC BoF at OLS this year)

 For example on the mpc52xx (see arch/ppc/syslib/mpc52xx_devices.c);
   - 6 PSC devices on chip;
   - (struct platform_device) for each device has: .name='mpc52xx-psc';
   - However, SCC1 may be driven by the Ethernet driver but PSC2 and
PSC6 may be serial
   - problem then is: How do you get only PSC1 bound to the
psc-ethernet driver and only PSC2 & PSC6 bound to the serial driver?

Possible solution;  Modify the naming scheme slightly from what is
currently used.
1. Make the Ethernet driver register the name "mpc52xx-psc:eth"
2. Make the serial driver register the name "mpc52xx-psc:uart"
3. In the board-specific platform code, modify the .name field in
struct platform_device *before* the device is registered with the
platform device. (possibly by extending ppc_sys_device_fixup callback)
   - The board specific code would set PSC1 to "mpc52xx-psc:eth",
PSC2&6 to "mpc52xx-psc:uart".  PSC3-5 would stick with "mpc52xx-psc"
and so would not get bound to anything.

Q: Can the .name field be modified *after* platform_device is
registered w/ the platform bus?

g.