linux-kernel - Re: [PATCH] usb: dwc2: dwc2_vbus_supply

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Date:   Thu, 22 Mar 2018 12:21:37 +0000
From:   Amelie DELAUNAY <amelie.delaunay@...com>
To:     Heiko Stübner <heiko@...ech.de>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Felipe Balbi" <felipe.balbi@...ux.intel.com>,
        Minas Harutyunyan <hminas@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc2: dwc2_vbus_supply_init: fix error check

Hi Heiko,
Hi Tomeu,

On 03/22/2018 12:41 PM, Heiko Stübner wrote:
> Hi Tomeu,
> 
> Am Donnerstag, 22. März 2018, 12:39:13 CET schrieb Heiko Stübner:
>> Am Donnerstag, 22. März 2018, 10:39:43 CET schrieb Tomeu Vizoso:
>>> devm_regulator_get_optional returns -ENODEV if the regulator isn't
>>> there, so if that's the case we have to make sure not to leave -ENODEV
>>> in the regulator pointer.
>>>
>>> Also, make sure we return 0 in that case, but correctly propagate any
>>> other errors. Also propagate the error from _dwc2_hcd_start.
>>>
>>> Fixes: 531ef5ebea96 ("usb: dwc2: add support for host mode external vbus
>>> supply") Cc: Amelie Delaunay <amelie.delaunay@...com>
>>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
>>
>> Thanks for catching that oops in your tests.
>> Reviewed-by: Heiko Stuebner <heiko@...ech.de>
> 
> I take that back :-)
> see below
> 
>>> ---
>>>
>>>   drivers/usb/dwc2/hcd.c | 13 ++++++++-----
>>>   1 file changed, 8 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
>>> index dcfda5eb4cac..4ae211f65e85 100644
>>> --- a/drivers/usb/dwc2/hcd.c
>>> +++ b/drivers/usb/dwc2/hcd.c
>>> @@ -359,8 +359,13 @@ static void dwc2_gusbcfg_init(struct dwc2_hsotg
>>> *hsotg) static int dwc2_vbus_supply_init(struct dwc2_hsotg *hsotg)
>>>
>>>   {
>>>   
>>>   	hsotg->vbus_supply = devm_regulator_get_optional(hsotg->dev, "vbus");
>>>
>>> -	if (IS_ERR(hsotg->vbus_supply))
>>> -		return 0;
>>> +	if (IS_ERR(hsotg->vbus_supply)) {
>>> +		hsotg->vbus_supply = NULL;
>>> +		if (PTR_ERR(hsotg->vbus_supply) == -ENODEV)
> 
> hsotg->vbus_supply is already NULL here
> 

Tomeu is right, here, hsotg->vbus_supply = ERR_PTR(-ENODEV).
/**
  * regulator_get_optional - obtain optional access to a regulator.
  * ...
  * Returns a struct regulator corresponding to the regulator producer,
  * or IS_ERR() condition containing errno.
  * ...
  */

You can add my Reviewed-by: Amelie Delaunay <amelie.delaunay@...com>

Thanks for the fix,
Amelie