linux-kernel - Re: [PATCH v4] usb: dwc2: dwc2_vbus_supply

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Date:   Tue, 10 Apr 2018 13:52:25 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Heiko Stuebner <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>,
        Amelie Delaunay <amelie.delaunay@...com>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v4] usb: dwc2: dwc2_vbus_supply_init: fix error check

Hi Heiko,

On 4/10/2018 4:28 PM, Heiko Stuebner wrote:
> Am Montag, 26. März 2018, 11:00:01 CEST 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>
> 
> The patch that gets fixed here also breaks display-output on dwc2-based
> Rockchip devices (likely even more), probably due to making the regulator
> framework hickup.
> 
Could you please elaborate what mean "breaks display-output".
On which Kernel version you apply this patch?

Thanks,
Minas


> With this patch applied, apart from not seeing the NULL-ptr, I also get
> display output on my rk3288-veycron Chromebook again, so
> 
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> 
> 
>> v2: Only overwrite the error in the pointer after checking it (Heiko
>>      Stübner <heiko@...ech.de>)
>> v3: Remove hunks that shouldn't be in this patch
>> v4: Don't overwrite the error code before returning it (kbuild test
>>      robot <lkp@...el.com>)
>> ---
>>   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 190f95964000..c51b73b3e048 100644
>> --- a/drivers/usb/dwc2/hcd.c
>> +++ b/drivers/usb/dwc2/hcd.c
>> @@ -358,9 +358,14 @@ static void dwc2_gusbcfg_init(struct dwc2_hsotg *hsotg)
>>   
>>   static int dwc2_vbus_supply_init(struct dwc2_hsotg *hsotg)
>>   {
>> +	int ret;
>> +
>>   	hsotg->vbus_supply = devm_regulator_get_optional(hsotg->dev, "vbus");
>> -	if (IS_ERR(hsotg->vbus_supply))
>> -		return 0;
>> +	if (IS_ERR(hsotg->vbus_supply)) {
>> +		ret = PTR_ERR(hsotg->vbus_supply);
>> +		hsotg->vbus_supply = NULL;
>> +		return ret == -ENODEV ? 0 : ret;
>> +	}
>>   
>>   	return regulator_enable(hsotg->vbus_supply);
>>   }
>> @@ -4342,9 +4347,7 @@ static int _dwc2_hcd_start(struct usb_hcd *hcd)
>>   
>>   	spin_unlock_irqrestore(&hsotg->lock, flags);
>>   
>> -	dwc2_vbus_supply_init(hsotg);
>> -
>> -	return 0;
>> +	return dwc2_vbus_supply_init(hsotg);
>>   }
>>   
>>   /*
>>
> 
> 
>