[PATCH 1/2] phy-sun4i-usb: Add sun4i_usb_phy_force_session_end() function

[Hans de Goede]

Hi,

On 09/22/2016 05:28 AM, Bin Liu wrote:
> Hi,
>
> On Wed, Sep 21, 2016 at 11:05:33AM +0300, Hans de Goede wrote:
>> Hi,
>>
>> On 09/20/2016 07:45 AM, Kishon Vijay Abraham I wrote:
>>> Hi,
>>>
>>> On Sunday 18 September 2016 10:20 PM, Hans de Goede wrote:
>>>> The sunxi musb has a bug where sometimes it will generate a babble
>>>> error on device disconnect instead of a disconnect irq. When this
>>>> happens the musb-controller switches from host mode to device mode
>>>> (it clears MUSB_DEVCTL_SESSION and sets MUSB_DEVCTL_BDEVICE) and
>>>> gets stuck in this state.
>>>>
>>>> Clearing this requires reporting Vbus low for 200 or more ms, but
>>>> on some devices Vbus is simply always high (host-only mode, no Vbus
>>>> control). The phy-sun4i-usb code already has code to force a session
>>>> end for devices without Vbus control.
>>>>
>>>> This commit adds a sun4i_usb_phy_force_session_end() function exporting
>>>> this functionality to the sunxi-musb glue, so that it can force a session
>>>> end to fixup the stuck state after a babble error.
>>>>
>>>> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
>>>> ---
>>>> drivers/phy/phy-sun4i-usb.c       | 11 +++++++++++
>>>> include/linux/phy/phy-sun4i-usb.h |  7 +++++++
>>>> 2 files changed, 18 insertions(+)
>>>>
>>>> diff --git a/drivers/phy/phy-sun4i-usb.c b/drivers/phy/phy-sun4i-usb.c
>>>> index 43c0d98..06f4e11a 100644
>>>> --- a/drivers/phy/phy-sun4i-usb.c
>>>> +++ b/drivers/phy/phy-sun4i-usb.c
>>>> @@ -470,6 +470,17 @@ void sun4i_usb_phy_set_squelch_detect(struct phy *_phy, bool enabled)
>>>> }
>>>> EXPORT_SYMBOL_GPL(sun4i_usb_phy_set_squelch_detect);
>>>>
>>>> +void sun4i_usb_phy_force_session_end(struct phy *_phy)
>>>> +{
>>>> +	struct sun4i_usb_phy *phy = phy_get_drvdata(_phy);
>>>> +	struct sun4i_usb_phy_data *data = to_sun4i_usb_phy_data(phy);
>>>> +
>>>> +	data->id_det = -1;
>>>> +	data->force_session_end = true;
>>>> +	queue_delayed_work(system_wq, &data->detect, 0);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(sun4i_usb_phy_force_session_end);
>>>
>>> Er.. one more export symbol :-(
>>
>> Yes unfortunately we need one more to work around sunxi musb / phy bugs.
>
> Instead, can you somehow reuse sun4i_usb_phy_set_mode()?

That was my first thought too, and I looked into this, but it did not
work out.

Regards,

Hans

>
> Regards,
> -Bin.
>
>>
>>>> +
>>>> static const struct phy_ops sun4i_usb_phy_ops = {
>>>> 	.init		= sun4i_usb_phy_init,
>>>> 	.exit		= sun4i_usb_phy_exit,
>>>> diff --git a/include/linux/phy/phy-sun4i-usb.h b/include/linux/phy/phy-sun4i-usb.h
>>>> index 50aed92..3bb773f 100644
>>>> --- a/include/linux/phy/phy-sun4i-usb.h
>>>> +++ b/include/linux/phy/phy-sun4i-usb.h
>>>> @@ -23,4 +23,11 @@
>>>>  */
>>>> void sun4i_usb_phy_set_squelch_detect(struct phy *phy, bool enabled);
>>>>
>>>> +/**
>>>> + * sun4i_usb_force_session_end() - Force the current session to end
>>>> + *				   by reporting VBus low for 200+ ms
>>>> + * @phy: reference to a sun4i usb phy
>>>> + */
>>>> +void sun4i_usb_phy_force_session_end(struct phy *phy);
>>>
>>> Should we include a static inline function if sun4i phy is not defined?
>>
>> No, we're also not doing that for the already exported
>> sun4i_usb_phy_set_squelch_detect()
>>
>> And it is not necessary since the only caller is drivers/usb/musb/sunxi.c,
>> and drivers/usb/musb/Kconfig has:
>>
>> config USB_MUSB_SUNXI
>>         tristate "Allwinner (sunxi)"
>>         depends on PHY_SUN4I_USB
>>
>> Regards,
>>
>> Hans