[PATCH v2 2/2] usb: dwc2: host: Clear interrupts before handling them

Douglas Anderson
2015-11-03T20:31:49Z

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.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
Changes in v2: None

drivers/usb/dwc2/core_intr.c | 55 ++++++++++++++++++++++----------------------
drivers/usb/dwc2/hcd_intr.c | 16 ++++++-------
2 files changed, 35 insertions(+), 36 deletions(-)

diff --git a/drivers/usb/dwc2/core_intr.c b/drivers/usb/dwc2/core_intr.c
index 61601d16e233..2a166b7eec41 100644
--- a/drivers/usb/dwc2/core_intr.c
+++ b/drivers/usb/dwc2/core_intr.c
@@ -80,15 +80,16 @@ static const char *dwc2_op_state_str(struct dwc2_hsotg *hsotg)
*/
static void dwc2_handle_usb_port_intr(struct dwc2_hsotg *hsotg)
{
- u32 hprt0 = dwc2_readl(hsotg->regs + HPRT0);
+ u32 hprt0;

+ /* Clear interrupt */
+ dwc2_writel(GINTSTS_PRTINT, hsotg->regs + GINTSTS);
+
+ hprt0 = dwc2_readl(hsotg->regs + HPRT0);
if (hprt0 & HPRT0_ENACHG) {
hprt0 &= ~HPRT0_ENA;
dwc2_writel(hprt0, hsotg->regs + HPRT0);
}
-
- /* Clear interrupt */
- dwc2_writel(GINTSTS_PRTINT, hsotg->regs + GINTSTS);
}

/**
@@ -98,11 +99,11 @@ 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 +277,13 @@ 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 +300,6 @@ 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 +317,12 @@ 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 +349,10 @@ 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 +374,9 @@ 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 +390,6 @@ 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 +398,14 @@ 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 +421,9 @@ 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 +442,7 @@ 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 +481,6 @@ 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..4c7f709b8182 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) {
+ 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) {
+ 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 +377,12 @@ static void dwc2_port_intr(struct dwc2_hsotg *hsotg)

/* Overcurrent Change Interrupt */
if (hprt0 & HPRT0_OVRCURRCHG) {
+ 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