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

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Date:   Wed, 1 Nov 2023 08:48:48 +0100
From:   Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:     Stanley Chang[昌育德] 
        <stanley_chang@...ltek.com>
Cc:     "Thinh.Nguyen@...opsys.com" <Thinh.Nguyen@...opsys.com>,
        "conor+dt@...nel.org" <conor+dt@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
Subject: Re: RE: [PATCH v6 1/2] usb: dwc3: add Realtek DHC RTD SoC dwc3 glue
 layer driver

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

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); }
>>> +
>>
>> ...
>