From mboxrd@z Thu Jan  1 00:00:00 1970
From: hdegoede@redhat.com (Hans de Goede)
Date: Wed, 21 Sep 2016 11:05:33 +0300
Subject: [PATCH 1/2] phy-sun4i-usb: Add sun4i_usb_phy_force_session_end()
 function
In-Reply-To: <57E0BEDF.2020603@ti.com>
References: <20160918165018.24547-1-hdegoede@redhat.com>
 <57E0BEDF.2020603@ti.com>
Message-ID: <54119844-ce99-bf8c-fc6e-09bcc7523e4d@redhat.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

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@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.

>> +
>>  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