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

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Date:   Mon, 23 Apr 2018 15:24:04 +0200
From:   Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:     Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
Cc:     Heiko Stübner <heiko@...ech.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Amelie Delaunay <amelie.delaunay@...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,

could this patch be picked up, please? Or if for some reason it cannot
be, could the commit that introduced the regression be reverted?

It's causing some tests in KernelCI to fail:

https://storage.kernelci.org/next/master/next-20180423/arm/multi_v7_defconfig/lab-collabora/sleep-rk3288-veyron-jaq.html

Thanks,

Tomeu


On 11 April 2018 at 08:50, Minas Harutyunyan
<Minas.Harutyunyan@...opsys.com> wrote:
> Hi Heiko,
>
> On 4/10/2018 7:37 PM, Heiko Stübner wrote:
>> Am Dienstag, 10. April 2018, 15:52:25 CEST schrieb Minas Harutyunyan:
>>> 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?
>>
>> I think I may have written that poorly. _Without_ this patch I get
>> display breakage on the most recent torvalds/master (merge-window)
>> where "usb: dwc2: add support for host mode external vbus supply" is
>> applied and this patch fixes the issue.
>>
>> "breaks display output" means both hdmi + edp output are missing
>> also including the backlight staying off.
>>
>> The patch we're fixing here, causes a null-pointer dereference in the
>> regulator framework, which seems to also cause issues when other
>> regulators are enabled, which I think is what I'm seeing here.
>>
>>
> Thank you for clarification. Earlier you added "reviewed" tag, this
> feedback can assumed as "tested" tag.
>
> Thanks,
> Minas
>
>> Heiko
>>
>>>
>>> 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);
>>>>>
>>>>>    }
>>>>>
>>>>>    /*
>>
>>
>>
>