Re: [PATCH 10/10] drivers: misc: use module_platform_driver_probe()

From: Arnd Bergmann
Date: Wed Mar 20 2013 - 07:46:51 EST

On Wednesday 20 March 2013, Fabio Porcedda wrote:
> On Wed, Mar 20, 2013 at 11:20 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> > On Wednesday 20 March 2013, Fabio Porcedda wrote:
> >> I think we can check inside the deferred_probe_work_func()
> >> if the dev->probe function pointer is equal to platform_drv_probe_fail().
> >
> > I think it's too late by then, because that would only warn if we try to probe
> > it again, but when platform_driver_probe() does not succeed immediately, it
> Maybe you mean "does succeed immediately" ?

I mean in this code (simplified for the sake of discussion)

int __init_or_module platform_driver_probe(struct platform_driver *drv,
int (*probe)(struct platform_device *))
int retval, code;

drv->probe = probe;
retval = code = platform_driver_register(drv);

drv->probe = NULL;
if (code == 0 && list_empty(&drv->driver.p->klist_devices.k_list))
retval = -ENODEV;
drv->driver.probe = platform_drv_probe_fail;

if (code != retval)
return retval;

we assume that all devices are bound to drivers during the call to
platform_driver_register, and if the device list is empty afterwards,
we unregister the driver and will never get to the deferred probing

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