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Date: Tue, 3 Nov 2015 12:31:09 -0800
From: Doug Anderson <dianders@...omium.org>
To: John Youn <John.Youn@...opsys.com>
Cc: "balbi@...com" <balbi@...com>, Yunzhi Li <lyz@...k-chips.com>,
Heiko Stübner <heiko@...ech.de>,
"linux-rockchip@...ts.infradead.org"
<linux-rockchip@...ts.infradead.org>,
Julius Werner <jwerner@...omium.org>,
"gregory.herrero@...el.com" <gregory.herrero@...el.com>,
"yousaf.kaukab@...el.com" <yousaf.kaukab@...el.com>,
"dinguyen@...nsource.altera.com" <dinguyen@...nsource.altera.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] usb: dwc2: host: Fix missing device insertions
John,
On Fri, Oct 30, 2015 at 1:38 PM, John Youn <John.Youn@...opsys.com> wrote:
> On 10/16/2015 3:10 PM, Douglas Anderson wrote:
>> If you've got your interrupt signals bouncing a bit as you insert your
>> USB device, you might end up in a state when the device is connected but
>> the driver doesn't know it.
>>
>> Specifically, the observed order is:
>> 1. hardware sees connect
>> 2. hardware sees disconnect
>> 3. hardware sees connect
>> 4. dwc2_port_intr() - clears connect interrupt
>> 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>>
>> Now you'll be stuck with the cable plugged in and no further interrupts
>> coming in but the driver will think we're disconnected.
>>
>> We'll fix this by checking for the missing connect interrupt and
>> re-connecting after the disconnect is posted. We don't skip the
>> disconnect because if there is a transitory disconnect we really want to
>> de-enumerate and re-enumerate.
>>
>> Signed-off-by: Douglas Anderson <dianders@...omium.org>
>> ---
>> drivers/usb/dwc2/core.h | 2 ++
>> drivers/usb/dwc2/hcd.c | 33 +++++++++++++++++++++++++++++++++
>> drivers/usb/dwc2/hcd_intr.c | 6 +-----
>> 3 files changed, 36 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
>> index ebf2504..30748be 100644
>> --- a/drivers/usb/dwc2/core.h
>> +++ b/drivers/usb/dwc2/core.h
>> @@ -1151,11 +1151,13 @@ static inline int dwc2_hsotg_set_test_mode(struct dwc2_hsotg *hsotg,
>>
>> #if IS_ENABLED(CONFIG_USB_DWC2_HOST) || IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)
>> extern int dwc2_hcd_get_frame_number(struct dwc2_hsotg *hsotg);
>> +extern void dwc2_hcd_connect(struct dwc2_hsotg *hsotg);
>> extern void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg);
>> extern void dwc2_hcd_start(struct dwc2_hsotg *hsotg);
>> #else
>> static inline int dwc2_hcd_get_frame_number(struct dwc2_hsotg *hsotg)
>> { return 0; }
>> +static inline void dwc2_hcd_connect(struct dwc2_hsotg *hsotg) {}
>> static inline void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg) {}
>> static inline void dwc2_hcd_start(struct dwc2_hsotg *hsotg) {}
>> static inline void dwc2_hcd_remove(struct dwc2_hsotg *hsotg) {}
>> diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
>> index af4e4a2..4d2bc50 100644
>> --- a/drivers/usb/dwc2/hcd.c
>> +++ b/drivers/usb/dwc2/hcd.c
>> @@ -268,6 +268,22 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
>> }
>>
>> /**
>> + * dwc2_hcd_connect() - Handles connect of the HCD
>> + *
>> + * @hsotg: Pointer to struct dwc2_hsotg
>> + *
>> + * Must be called with interrupt disabled and spinlock held
>> + */
>> +void dwc2_hcd_connect(struct dwc2_hsotg *hsotg)
>> +{
>> + if (hsotg->lx_state != DWC2_L0)
>> + usb_hcd_resume_root_hub(hsotg->priv);
>> +
>> + hsotg->flags.b.port_connect_status_change = 1;
>> + hsotg->flags.b.port_connect_status = 1;
>> +}
>> +
>> +/**
>> * dwc2_hcd_disconnect() - Handles disconnect of the HCD
>> *
>> * @hsotg: Pointer to struct dwc2_hsotg
>> @@ -277,6 +293,7 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
>> void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
>> {
>> u32 intr;
>> + u32 hprt0;
>>
>> /* Set status flags for the hub driver */
>> hsotg->flags.b.port_connect_status_change = 1;
>> @@ -315,6 +332,22 @@ void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
>> dwc2_hcd_cleanup_channels(hsotg);
>>
>> dwc2_host_disconnect(hsotg);
>> +
>> + /*
>> + * Add an extra check here to see if we're actually connected but
>> + * we don't have a detection interrupt pending. This can happen if:
>> + * 1. hardware sees connect
>> + * 2. hardware sees disconnect
>> + * 3. hardware sees connect
>> + * 4. dwc2_port_intr() - clears connect interrupt
>> + * 5. dwc2_handle_common_intr() - calls here
>> + *
>> + * Without the extra check here we will end calling disconnect
>> + * and won't get any future interrupts to handle the connect.
>> + */
>> + hprt0 = dwc2_readl(hsotg->regs + HPRT0);
>> + if (!(hprt0 & HPRT0_CONNDET) && (hprt0 & HPRT0_CONNSTS))
>> + dwc2_hcd_connect(hsotg);
>
> I'm a little bit wary of this as it will also run when you unload
> the module with a device connected. However I can't produce any
> negative results from that. Will it work if you handle it just
> for the disconnect interrupt?
Good call. I think it might actually be cleaner to just add a "force"
parameter to dwc2_hcd_disconnect(). That way the 3 callers other than
_dwc2_hcd_stop() all get the behavior to check for reconnect. I hope
that's OK. New patch forthcoming.
-Doug
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