[PATCH v4 1/2] usb: dwc2: host: Fix missing device insertions

[PATCH v4 1/2] usb: dwc2: host: Fix missing device insertions

[Douglas Anderson]

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.

Notes:
1. As part of this change we add a "force" parameter to
   dwc2_hcd_disconnect() so that when we're unloading the module we
   avoid the new behavior.  The need for this was pointed out by John
   Youn.
2. The bit of code needed at the end of dwc2_hcd_disconnect() is
   exactly the same bit of code from dwc2_port_intr().  To avoid
   duplication, we refactor that code out into a new function
   dwc2_hcd_connect().

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: John Youn <johnyoun@synopsys.com>
---
Changes in v4: None
Changes in v3:
- Add notes to device insertions commit message (Felipe Balbi)

Changes in v2:
- Don't reconnect when called from _dwc2_hcd_stop() (John Youn)

 drivers/usb/dwc2/core.h      |  6 ++++--
 drivers/usb/dwc2/core_intr.c |  4 ++--
 drivers/usb/dwc2/hcd.c       | 40 ++++++++++++++++++++++++++++++++++++++--
 drivers/usb/dwc2/hcd_intr.c  |  6 +-----
 4 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
index a66d3cb62b65..daa1c342cdac 100644
--- a/drivers/usb/dwc2/core.h
+++ b/drivers/usb/dwc2/core.h
@@ -1154,12 +1154,14 @@ 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_disconnect(struct dwc2_hsotg *hsotg);
+extern void dwc2_hcd_connect(struct dwc2_hsotg *hsotg);
+extern void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force);
 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_disconnect(struct dwc2_hsotg *hsotg) {}
+static inline void dwc2_hcd_connect(struct dwc2_hsotg *hsotg) {}
+static inline void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force) {}
 static inline void dwc2_hcd_start(struct dwc2_hsotg *hsotg) {}
 static inline void dwc2_hcd_remove(struct dwc2_hsotg *hsotg) {}
 static inline int dwc2_hcd_init(struct dwc2_hsotg *hsotg, int irq)
diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
index 27daa42788b1..61601d16e233 100644
--- a/drivers/usb/dwc2/core_intr.c
+++ b/drivers/usb/dwc2/core_intr.c
@@ -239,7 +239,7 @@ static void dwc2_handle_otg_intr(struct dwc2_hsotg *hsotg)
 			dev_dbg(hsotg->dev, "a_suspend->a_peripheral (%d)\n",
 				hsotg->op_state);
 			spin_unlock(&hsotg->lock);
-			dwc2_hcd_disconnect(hsotg);
+			dwc2_hcd_disconnect(hsotg, false);
 			spin_lock(&hsotg->lock);
 			hsotg->op_state = OTG_STATE_A_PERIPHERAL;
 		} else {
@@ -401,7 +401,7 @@ static void dwc2_handle_disconnect_intr(struct dwc2_hsotg *hsotg)
 		dwc2_op_state_str(hsotg));
 
 	if (hsotg->op_state == OTG_STATE_A_HOST)
-		dwc2_hcd_disconnect(hsotg);
+		dwc2_hcd_disconnect(hsotg, false);
 
 	dwc2_writel(GINTSTS_DISCONNINT, hsotg->regs + GINTSTS);
 }
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index e79baf73c234..e208eac7ff57 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -268,15 +268,33 @@ 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
+ * @force: If true, we won't try to reconnect even if we see device connected.
  *
  * Must be called with interrupt disabled and spinlock held
  */
-void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg)
+void dwc2_hcd_disconnect(struct dwc2_hsotg *hsotg, bool force)
 {
 	u32 intr;
+	u32 hprt0;
 
 	/* Set status flags for the hub driver */
 	hsotg->flags.b.port_connect_status_change = 1;
@@ -315,6 +333,24 @@ 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.
+	 */
+	if (!force) {
+		hprt0 = dwc2_readl(hsotg->regs + HPRT0);
+		if (!(hprt0 & HPRT0_CONNDET) && (hprt0 & HPRT0_CONNSTS))
+			dwc2_hcd_connect(hsotg);
+	}
 }
 
 /**
@@ -2365,7 +2401,7 @@ static void _dwc2_hcd_stop(struct usb_hcd *hcd)
 
 	spin_lock_irqsave(&hsotg->lock, flags);
 	/* Ensure hcd is disconnected */
-	dwc2_hcd_disconnect(hsotg);
+	dwc2_hcd_disconnect(hsotg, true);
 	dwc2_hcd_stop(hsotg);
 	hsotg->lx_state = DWC2_L3;
 	hcd->state = HC_STATE_HALT;
diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c
index bda0b21b850f..03504ac2fecc 100644
--- a/drivers/usb/dwc2/hcd_intr.c
+++ b/drivers/usb/dwc2/hcd_intr.c
@@ -350,11 +350,7 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
 		dev_vdbg(hsotg->dev,
 			 "--Port Interrupt HPRT0=0x%08x Port Connect Detected--\n",
 			 hprt0);
-		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_connect(hsotg);
 		hprt0_modify |= HPRT0_CONNDET;
 
 		/*
-- 
2.6.0.rc2.230.g3dd15c0

[PATCH v4 2/2] usb: dwc2: host: Clear interrupts before handling them

[Douglas Anderson]

In general it is wise to clear interrupts before processing them.  If
you don't do that, you can get:
 1. Interrupt happens
 2. You look at system state and process interrupt
 3. A new interrupt happens
 4. You clear interrupt without processing it.

This patch was actually a first attempt to fix missing device insertions
as described in (usb: dwc2: host: Fix missing device insertions) and it
did solve some of the signal bouncing problems but not all of
them (which is why I submitted the other patch).  Specifically, this
patch itself would sometimes change:
 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()

...to:
 1. hardware sees connect
 2. hardware sees disconnect
 3. dwc2_port_intr() - clears connect interrupt
 4. hardware sees connect
 5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()

...but with different timing then sometimes we'd still miss cable
insertions.

In any case, though this patch doesn't fix any (known) problems, it
still seems wise as a general policy to clear interrupt before handling
them.

Note that for dwc2_handle_usb_port_intr(), instead of moving the clear
of PRTINT to the beginning of the function we remove it completely.  The
only way to clear PRTINT is to clear the sources that set it in the
first place.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Tested-by: John Youn <johnyoun@synopsys.com>
---
Changes in v4:
- Don't replace dwc2_writel with writel (Antti Seppälä).
- Update description to explain why we remove PRTINT clear.

Changes in v3:
- Don't (uselessly) clear the PRTINT anymore (Felipe Balbi).

Changes in v2: None

 drivers/usb/dwc2/core_intr.c | 49 +++++++++++++++++++++-----------------------
 drivers/usb/dwc2/hcd_intr.c  | 17 ++++++++-------
 2 files changed, 31 insertions(+), 35 deletions(-)

diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
index 61601d16e233..d85c5c9f96c1 100644
--- a/drivers/usb/dwc2/core_intr.c
+++ b/drivers/usb/dwc2/core_intr.c
@@ -86,9 +86,6 @@ static void dwc2_handle_usb_port_intr(struct dwc2_hsotg *hsotg)
 		hprt0 &= ~HPRT0_ENA;
 		dwc2_writel(hprt0, hsotg->regs + HPRT0);
 	}
-
-	/* Clear interrupt */
-	dwc2_writel(GINTSTS_PRTINT, hsotg->regs + GINTSTS);
 }
 
 /**
@@ -98,11 +95,11 @@ static void dwc2_handle_usb_port_intr(struct dwc2_hsotg *hsotg)
  */
 static void dwc2_handle_mode_mismatch_intr(struct dwc2_hsotg *hsotg)
 {
-	dev_warn(hsotg->dev, "Mode Mismatch Interrupt: currently in %s mode\n",
-		 dwc2_is_host_mode(hsotg) ? "Host" : "Device");
-
 	/* Clear interrupt */
 	dwc2_writel(GINTSTS_MODEMIS, hsotg->regs + GINTSTS);
+
+	dev_warn(hsotg->dev, "Mode Mismatch Interrupt: currently in %s mode\n",
+		 dwc2_is_host_mode(hsotg) ? "Host" : "Device");
 }
 
 /**
@@ -276,9 +273,13 @@ static void dwc2_handle_otg_intr(struct dwc2_hsotg *hsotg)
  */
 static void dwc2_handle_conn_id_status_change_intr(struct dwc2_hsotg *hsotg)
 {
-	u32 gintmsk = dwc2_readl(hsotg->regs + GINTMSK);
+	u32 gintmsk;
+
+	/* Clear interrupt */
+	dwc2_writel(GINTSTS_CONIDSTSCHNG, hsotg->regs + GINTSTS);
 
 	/* Need to disable SOF interrupt immediately */
+	gintmsk = dwc2_readl(hsotg->regs + GINTMSK);
 	gintmsk &= ~GINTSTS_SOF;
 	dwc2_writel(gintmsk, hsotg->regs + GINTMSK);
 
@@ -295,9 +296,6 @@ static void dwc2_handle_conn_id_status_change_intr(struct dwc2_hsotg *hsotg)
 		queue_work(hsotg->wq_otg, &hsotg->wf_otg);
 		spin_lock(&hsotg->lock);
 	}
-
-	/* Clear interrupt */
-	dwc2_writel(GINTSTS_CONIDSTSCHNG, hsotg->regs + GINTSTS);
 }
 
 /**
@@ -315,12 +313,12 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
 {
 	int ret;
 
-	dev_dbg(hsotg->dev, "Session request interrupt - lx_state=%d\n",
-							hsotg->lx_state);
-
 	/* Clear interrupt */
 	dwc2_writel(GINTSTS_SESSREQINT, hsotg->regs + GINTSTS);
 
+	dev_dbg(hsotg->dev, "Session request interrupt - lx_state=%d\n",
+							hsotg->lx_state);
+
 	if (dwc2_is_device_mode(hsotg)) {
 		if (hsotg->lx_state == DWC2_L2) {
 			ret = dwc2_exit_hibernation(hsotg, true);
@@ -347,6 +345,10 @@ static void dwc2_handle_session_req_intr(struct dwc2_hsotg *hsotg)
 static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
 {
 	int ret;
+
+	/* Clear interrupt */
+	dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
+
 	dev_dbg(hsotg->dev, "++Resume or Remote Wakeup Detected Interrupt++\n");
 	dev_dbg(hsotg->dev, "%s lxstate = %d\n", __func__, hsotg->lx_state);
 
@@ -368,10 +370,9 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
 		/* Change to L0 state */
 		hsotg->lx_state = DWC2_L0;
 	} else {
-		if (hsotg->core_params->hibernation) {
-			dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
+		if (hsotg->core_params->hibernation)
 			return;
-		}
+
 		if (hsotg->lx_state != DWC2_L1) {
 			u32 pcgcctl = dwc2_readl(hsotg->regs + PCGCTL);
 
@@ -385,9 +386,6 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
 			hsotg->lx_state = DWC2_L0;
 		}
 	}
-
-	/* Clear interrupt */
-	dwc2_writel(GINTSTS_WKUPINT, hsotg->regs + GINTSTS);
 }
 
 /*
@@ -396,14 +394,14 @@ static void dwc2_handle_wakeup_detected_intr(struct dwc2_hsotg *hsotg)
  */
 static void dwc2_handle_disconnect_intr(struct dwc2_hsotg *hsotg)
 {
+	dwc2_writel(GINTSTS_DISCONNINT, hsotg->regs + GINTSTS);
+
 	dev_dbg(hsotg->dev, "++Disconnect Detected Interrupt++ (%s) %s\n",
 		dwc2_is_host_mode(hsotg) ? "Host" : "Device",
 		dwc2_op_state_str(hsotg));
 
 	if (hsotg->op_state == OTG_STATE_A_HOST)
 		dwc2_hcd_disconnect(hsotg, false);
-
-	dwc2_writel(GINTSTS_DISCONNINT, hsotg->regs + GINTSTS);
 }
 
 /*
@@ -419,6 +417,9 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg)
 	u32 dsts;
 	int ret;
 
+	/* Clear interrupt */
+	dwc2_writel(GINTSTS_USBSUSP, hsotg->regs + GINTSTS);
+
 	dev_dbg(hsotg->dev, "USB SUSPEND\n");
 
 	if (dwc2_is_device_mode(hsotg)) {
@@ -437,7 +438,7 @@ static void dwc2_handle_usb_suspend_intr(struct dwc2_hsotg *hsotg)
 			if (!dwc2_is_device_connected(hsotg)) {
 				dev_dbg(hsotg->dev,
 						"ignore suspend request before enumeration\n");
-				goto clear_int;
+				return;
 			}
 
 			ret = dwc2_enter_hibernation(hsotg);
@@ -476,10 +477,6 @@ skip_power_saving:
 			hsotg->op_state = OTG_STATE_A_HOST;
 		}
 	}
-
-clear_int:
-	/* Clear interrupt */
-	dwc2_writel(GINTSTS_USBSUSP, hsotg->regs + GINTSTS);
 }
 
 #define GINTMSK_COMMON	(GINTSTS_WKUPINT | GINTSTS_SESSREQINT |		\
diff --git a/drivers/usb/dwc2/hcd_intr.c b/drivers/usb/dwc2/hcd_intr.c
index 03504ac2fecc..bc3452355cfd 100644
--- a/drivers/usb/dwc2/hcd_intr.c
+++ b/drivers/usb/dwc2/hcd_intr.c
@@ -122,6 +122,9 @@ static void dwc2_sof_intr(struct dwc2_hsotg *hsotg)
 	struct dwc2_qh *qh;
 	enum dwc2_transaction_type tr_type;
 
+	/* Clear interrupt */
+	dwc2_writel(GINTSTS_SOF, hsotg->regs + GINTSTS);
+
 #ifdef DEBUG_SOF
 	dev_vdbg(hsotg->dev, "--Start of Frame Interrupt--\n");
 #endif
@@ -146,9 +149,6 @@ static void dwc2_sof_intr(struct dwc2_hsotg *hsotg)
 	tr_type = dwc2_hcd_select_transactions(hsotg);
 	if (tr_type != DWC2_TRANSACTION_NONE)
 		dwc2_hcd_queue_transactions(hsotg, tr_type);
-
-	/* Clear interrupt */
-	dwc2_writel(GINTSTS_SOF, hsotg->regs + GINTSTS);
 }
 
 /*
@@ -347,11 +347,12 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
 	 * Set flag and clear if detected
 	 */
 	if (hprt0 & HPRT0_CONNDET) {
+		dwc2_writel(hprt0_modify | HPRT0_CONNDET, hsotg->regs + HPRT0);
+
 		dev_vdbg(hsotg->dev,
 			 "--Port Interrupt HPRT0=0x%08x Port Connect Detected--\n",
 			 hprt0);
 		dwc2_hcd_connect(hsotg);
-		hprt0_modify |= HPRT0_CONNDET;
 
 		/*
 		 * The Hub driver asserts a reset when it sees port connect
@@ -364,10 +365,10 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
 	 * Clear if detected - Set internal flag if disabled
 	 */
 	if (hprt0 & HPRT0_ENACHG) {
+		dwc2_writel(hprt0_modify | HPRT0_ENACHG, hsotg->regs + HPRT0);
 		dev_vdbg(hsotg->dev,
 			 "  --Port Interrupt HPRT0=0x%08x Port Enable Changed (now %d)--\n",
 			 hprt0, !!(hprt0 & HPRT0_ENA));
-		hprt0_modify |= HPRT0_ENACHG;
 		if (hprt0 & HPRT0_ENA)
 			dwc2_hprt0_enable(hsotg, hprt0, &hprt0_modify);
 		else
@@ -376,15 +377,13 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)
 
 	/* Overcurrent Change Interrupt */
 	if (hprt0 & HPRT0_OVRCURRCHG) {
+		dwc2_writel(hprt0_modify | HPRT0_OVRCURRCHG,
+			    hsotg->regs + HPRT0);
 		dev_vdbg(hsotg->dev,
 			 "  --Port Interrupt HPRT0=0x%08x Port Overcurrent Changed--\n",
 			 hprt0);
 		hsotg->flags.b.port_over_current_change = 1;
-		hprt0_modify |= HPRT0_OVRCURRCHG;
 	}
-
-	/* Clear Port Interrupts */
-	dwc2_writel(hprt0_modify, hsotg->regs + HPRT0);
 }
 
 /*
-- 
2.6.0.rc2.230.g3dd15c0

Re: [PATCH v4 2/2] usb: dwc2: host: Clear interrupts before handling them

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 2000 bytes --]


Hi,

Douglas Anderson <dianders@chromium.org> writes:
> In general it is wise to clear interrupts before processing them.  If
> you don't do that, you can get:
>  1. Interrupt happens
>  2. You look at system state and process interrupt
>  3. A new interrupt happens
>  4. You clear interrupt without processing it.
>
> This patch was actually a first attempt to fix missing device insertions
> as described in (usb: dwc2: host: Fix missing device insertions) and it
> did solve some of the signal bouncing problems but not all of
> them (which is why I submitted the other patch).  Specifically, this
> patch itself would sometimes change:
>  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()
>
> ...to:
>  1. hardware sees connect
>  2. hardware sees disconnect
>  3. dwc2_port_intr() - clears connect interrupt
>  4. hardware sees connect
>  5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>
> ...but with different timing then sometimes we'd still miss cable
> insertions.
>
> In any case, though this patch doesn't fix any (known) problems, it
> still seems wise as a general policy to clear interrupt before handling
> them.
>
> Note that for dwc2_handle_usb_port_intr(), instead of moving the clear
> of PRTINT to the beginning of the function we remove it completely.  The
> only way to clear PRTINT is to clear the sources that set it in the
> first place.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Acked-by: John Youn <johnyoun@synopsys.com>
> Tested-by: John Youn <johnyoun@synopsys.com>

$ patch -p1 --dry-run < patch.diff
checking file drivers/usb/dwc2/core_intr.c
checking file drivers/usb/dwc2/hcd_intr.c
Hunk #4 FAILED at 365.
Hunk #5 succeeded at 388 (offset 11 lines).
1 out of 5 hunks FAILED

Care to rebase on top of my testing/next ?

-- 
balbi

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 818 bytes --]

Re: [PATCH v4 2/2] usb: dwc2: host: Clear interrupts before handling them

[Doug Anderson]

Felipe,

On Fri, Nov 20, 2015 at 7:40 AM, Felipe Balbi <balbi@ti.com> wrote:
>
> Hi,
>
> Douglas Anderson <dianders@chromium.org> writes:
>> In general it is wise to clear interrupts before processing them.  If
>> you don't do that, you can get:
>>  1. Interrupt happens
>>  2. You look at system state and process interrupt
>>  3. A new interrupt happens
>>  4. You clear interrupt without processing it.
>>
>> This patch was actually a first attempt to fix missing device insertions
>> as described in (usb: dwc2: host: Fix missing device insertions) and it
>> did solve some of the signal bouncing problems but not all of
>> them (which is why I submitted the other patch).  Specifically, this
>> patch itself would sometimes change:
>>  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()
>>
>> ...to:
>>  1. hardware sees connect
>>  2. hardware sees disconnect
>>  3. dwc2_port_intr() - clears connect interrupt
>>  4. hardware sees connect
>>  5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>>
>> ...but with different timing then sometimes we'd still miss cable
>> insertions.
>>
>> In any case, though this patch doesn't fix any (known) problems, it
>> still seems wise as a general policy to clear interrupt before handling
>> them.
>>
>> Note that for dwc2_handle_usb_port_intr(), instead of moving the clear
>> of PRTINT to the beginning of the function we remove it completely.  The
>> only way to clear PRTINT is to clear the sources that set it in the
>> first place.
>>
>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
>> Acked-by: John Youn <johnyoun@synopsys.com>
>> Tested-by: John Youn <johnyoun@synopsys.com>
>
> $ patch -p1 --dry-run < patch.diff
> checking file drivers/usb/dwc2/core_intr.c
> checking file drivers/usb/dwc2/hcd_intr.c
> Hunk #4 FAILED at 365.
> Hunk #5 succeeded at 388 (offset 11 lines).
> 1 out of 5 hunks FAILED
>
> Care to rebase on top of my testing/next ?

No problem.

...though when I did that, I actually found (by code inspection) a bug
in the original patch, so I guess it's a good thing it didn't apply...
...and then that led me to another bug that was pre-existing.  I'll
send up two new patches shortly.  I'll remove John's Ack and Tested
tags from the patch since it contains a change.

It looks like you already landed part 1 of this series (usb: dwc2:
host: Fix missing device insertions) so I won't resend that.

-Doug

Re: [PATCH v4 2/2] usb: dwc2: host: Clear interrupts before handling them

[Doug Anderson]

Hi,

On Fri, Nov 20, 2015 at 8:49 AM, Doug Anderson <dianders@chromium.org> wrote:
> Felipe,
>
> On Fri, Nov 20, 2015 at 7:40 AM, Felipe Balbi <balbi@ti.com> wrote:
>>
>> Hi,
>>
>> Douglas Anderson <dianders@chromium.org> writes:
>>> In general it is wise to clear interrupts before processing them.  If
>>> you don't do that, you can get:
>>>  1. Interrupt happens
>>>  2. You look at system state and process interrupt
>>>  3. A new interrupt happens
>>>  4. You clear interrupt without processing it.
>>>
>>> This patch was actually a first attempt to fix missing device insertions
>>> as described in (usb: dwc2: host: Fix missing device insertions) and it
>>> did solve some of the signal bouncing problems but not all of
>>> them (which is why I submitted the other patch).  Specifically, this
>>> patch itself would sometimes change:
>>>  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()
>>>
>>> ...to:
>>>  1. hardware sees connect
>>>  2. hardware sees disconnect
>>>  3. dwc2_port_intr() - clears connect interrupt
>>>  4. hardware sees connect
>>>  5. dwc2_handle_common_intr() - calls dwc2_hcd_disconnect()
>>>
>>> ...but with different timing then sometimes we'd still miss cable
>>> insertions.
>>>
>>> In any case, though this patch doesn't fix any (known) problems, it
>>> still seems wise as a general policy to clear interrupt before handling
>>> them.
>>>
>>> Note that for dwc2_handle_usb_port_intr(), instead of moving the clear
>>> of PRTINT to the beginning of the function we remove it completely.  The
>>> only way to clear PRTINT is to clear the sources that set it in the
>>> first place.
>>>
>>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
>>> Acked-by: John Youn <johnyoun@synopsys.com>
>>> Tested-by: John Youn <johnyoun@synopsys.com>
>>
>> $ patch -p1 --dry-run < patch.diff
>> checking file drivers/usb/dwc2/core_intr.c
>> checking file drivers/usb/dwc2/hcd_intr.c
>> Hunk #4 FAILED at 365.
>> Hunk #5 succeeded at 388 (offset 11 lines).
>> 1 out of 5 hunks FAILED
>>
>> Care to rebase on top of my testing/next ?
>
> No problem.
>
> ...though when I did that, I actually found (by code inspection) a bug
> in the original patch, so I guess it's a good thing it didn't apply...
> ...and then that led me to another bug that was pre-existing.  I'll
> send up two new patches shortly.  I'll remove John's Ack and Tested
> tags from the patch since it contains a change.
>
> It looks like you already landed part 1 of this series (usb: dwc2:
> host: Fix missing device insertions) so I won't resend that.

Ah, OK.  Now I see why nobody found these problems in testing.  The
code path is completely disabled by all current parameters as checked
in to mainline.  In any case, it's good to fix.

-Doug