Am Sonntag 18 Dezember 2011, 09:10:48 schrieb Russell King - ARM Linux:
> On Sat, Dec 17, 2011 at 08:26:33PM +0100, Heiko Stübner wrote:
> > As the driver is also buildable as a module it should need
> > a cleanup function for the removal of the module.
>
> My guess is that this wasn't implemented because of the embedded struct
> device lifetime rules for the gadget - to prevent the unbinding of the
> driver.
>
> Until the struct device lifetime gets fixed, you must not allow the module
> nor the data structure containing the struct device to be freed.
I understand where this problem comes from (the release method is potentially
gone with the module before it is called) but after more reading, I have a
hard time believing that a lot of the other gadget drivers would be wrong as
well. Some of them since 2009 or possibly earlier.
Gadgets with embedded release methods: langwell_udc, goku_udc, fsl_qe_udc (and
fsl_udc_core), amd5536udc, net2280, pch_udc, cil13xxx_udc, dummy_hcd,
omap_udc, net2272, mc_udc_core
Gadgets which use the release method from its pdev->dev but also free the
struct with the gadget in their remove method: r8a66597-udc, m66592-udc,
fusb300_udc. (possibly before the release function is called)
On the other hand, the gets and puts of the udc->gadget.dev should be paired
correctly and it's only an intermediate device between the udc and the gadget
driver, so that the call to device_unregister in the remove method should put
the refcount to 0 and thus init the cleanup (including the call to release)
before the module is removed.
So, I am very confused :-).
Heiko
> > Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx>
> > ---
> >
> > drivers/usb/gadget/s3c-hsudc.c | 25 +++++++++++++++++++++++++
> > 1 files changed, 25 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/usb/gadget/s3c-hsudc.c
> > b/drivers/usb/gadget/s3c-hsudc.c index 3e5673d..7cb0850 100644
> > --- a/drivers/usb/gadget/s3c-hsudc.c
> > +++ b/drivers/usb/gadget/s3c-hsudc.c
> >
> > @@ -1370,12 +1370,37 @@ err_res:
> > return ret;
> >
> > }
> >
> > +static int __devexit s3c_hsudc_remove(struct platform_device *pdev)
> > +{
> > + struct s3c_hsudc *hsudc = the_controller;
> > +
> > + usb_del_gadget_udc(&hsudc->gadget);
> > +
> > + clk_disable(hsudc->uclk);
> > + clk_put(hsudc->uclk);
> > +
> > + free_irq(hsudc->irq, hsudc);
> > +
> > + iounmap(hsudc->regs);
> > +
> > + release_resource(hsudc->mem_rsrc);
> > + kfree(hsudc->mem_rsrc);
> > +
> > + if (hsudc->transceiver)
> > + otg_put_transceiver(hsudc->transceiver);
> > +
> > + the_controller = NULL;
> > + kfree(hsudc);
> > + return 0;
> > +}
> > +
> >
> > static struct platform_driver s3c_hsudc_driver = {
> >
> > .driver = {
> >
> > .owner = THIS_MODULE,
> > .name = "s3c-hsudc",
> >
> > },
> > .probe = s3c_hsudc_probe,
> >
> > + .remove = __devexit_p(s3c_hsudc_remove),
> >
> > };
> >
> > module_platform_driver(s3c_hsudc_driver);
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