Re: RE: RE: [PATCH v6 1/2] usb: dwc3: add Realtek DHC RTD SoC dwc3 glue layer driver

[Christophe JAILLET]

Le 03/11/2023 à 11:54, Stanley Chang[昌育德] a écrit :
> Hi Christophe,
>
> > Le 01/11/2023 à 07:27, Stanley Chang[昌育德] a écrit :
> > > Hi CJ,
> > >
> > > I think these functions are not needed in remove function.
> > >
> > > In dwc3_rtk_probe_dwc3_core,
> > > I have used
> > > dwc3_node = of_get_compatible_child(node, "snps,dwc3"); and dwc3_pdev
> > > = of_find_device_by_node(dwc3_node);
> > >
> > > So, I call these put functions.
> > > platform_device_put(dwc3_pdev);
> > > of_node_put(dwc3_node);
> >
> > Yes, but you call it only in the error handling path of the function.
> >
> > I wonder if they should also be called in the remove function in order to
> > decrement the ref-counted reference.
> >
> >
> > Same in __get_dwc3_maximum_speed(), the reference taken by:
> >      dwc3_np = of_get_compatible_child(np, "snps,dwc3"); is never released.
> >
> >
> > See the comment at [1] to see what I mean.
> >
> >
> > [1]: https://elixir.bootlin.com/linux/v6.6/source/drivers/of/base.c#L681
>
> You are right!
> For dwc3_pdev, dwc3_np or dwc3_node, I should add of_node_put to release them when the function exits.
> https://elixir.bootlin.com/linux/v6.5.10/source/drivers/usb/dwc3/dwc3-meson-g12a.c#L567
>
> I will add a patch to fix this.
>
> For example,
> diff --git a/drivers/usb/dwc3/dwc3-rtk.c b/drivers/usb/dwc3/dwc3-rtk.c
> index 590028e8fdcb..9d6f2a8bd6ce 100644
> --- a/drivers/usb/dwc3/dwc3-rtk.c
> +++ b/drivers/usb/dwc3/dwc3-rtk.c
> @@ -187,6 +187,7 @@ static enum usb_device_speed __get_dwc3_maximum_speed(struct device_node *np)
>
>          ret = match_string(speed_names, ARRAY_SIZE(speed_names), maximum_speed);
>
> +       of_node_put(dwc3_np);
>          return (ret < 0) ? USB_SPEED_UNKNOWN : ret;
>   }
>
> @@ -339,6 +340,8 @@ static int dwc3_rtk_probe_dwc3_core(struct dwc3_rtk *rtk)
>
>          switch_usb2_role(rtk, rtk->cur_role);
>
> +       platform_device_put(dwc3_pdev);
> +       of_node_put(dwc3_node);
>          return 0;
>
>   err_pdev_put:

LGTM.

CJ

> Thanks,
> Stanley
>
> > CJ
> > > Thanks,
> > > Stanley
> > >
> > > > Hi,
> > > >
> > > > Is something like
> > > >           platform_device_put(dwc3_pdev);
> > > >           of_node_put(dwc3_node);
> > > > needed in the remove function?
> > > >
> > > > (as done in the error handling path of dwc3_rtk_probe_dwc3_core())
> > > >
> > > > Or should it be added at the end of dwc3_rtk_probe_dwc3_core() if the
> > > > reference are nor needed anymore when we leave the function?
> > > >
> > > > CJ
> > > >
> > > > > +     of_platform_depopulate(rtk->dev); }
> > > > > +
> > > >
> > > > ...