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Message-ID: <1458133551-3071-3-git-send-email-rogerq@ti.com>
Date: Wed, 16 Mar 2016 15:05:51 +0200
From: Roger Quadros <rogerq@...com>
To: <balbi@...nel.org>
CC: <nsekhar@...com>, <linux-usb@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, Roger Quadros <rogerq@...com>
Subject: [PATCH 2/2] usb: dwc3: gadget: usb: dwc3: run/stop metastability workaround
The existing workaround of forcing DEVSPD to SUPER_SPEED
for HIGH_SPEED ports is causing another side effect
which causes erratic interrupts and delayed gadget
enumeration of upto 2 seconds.
Work around the run/stop issue by detecting if
it happened using debug LTSSM state and issuing
soft reset to the device controller when changing RUN_STOP
from 0 to 1.
We apply the workaround only if PRTCAP is DEVICE mode
as we don't yet support this workaround in OTG mode.
Use USB RESET event as exit condition for workaround.
Signed-off-by: Roger Quadros <rogerq@...com>
---
drivers/usb/dwc3/core.h | 1 +
drivers/usb/dwc3/gadget.c | 175 +++++++++++++++++++++++++++++++++++++---------
2 files changed, 144 insertions(+), 32 deletions(-)
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 2bea1ac..a724c0d 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -762,6 +762,7 @@ struct dwc3 {
struct usb_gadget gadget;
struct usb_gadget_driver *gadget_driver;
+ struct completion reset_event; /* used for run/stop workaround */
struct usb_phy *usb2_phy;
struct usb_phy *usb3_phy;
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 3ac170f..03418b8 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -35,6 +35,9 @@
#include "gadget.h"
#include "io.h"
+static void dwc3_gadget_disable_irq(struct dwc3 *dwc);
+static int dwc3_gadget_restart(struct dwc3 *dwc);
+
/**
* dwc3_gadget_set_test_mode - Enables USB2 Test Modes
* @dwc: pointer to our context structure
@@ -1570,13 +1573,100 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
struct dwc3 *dwc = gadget_to_dwc(g);
unsigned long flags;
int ret;
+ int trys = 0;
is_on = !!is_on;
+ if (is_on)
+ reinit_completion(&dwc->reset_event);
+
spin_lock_irqsave(&dwc->lock, flags);
ret = dwc3_gadget_run_stop(dwc, is_on, false);
spin_unlock_irqrestore(&dwc->lock, flags);
+try:
+ /**
+ * WORKAROUND: DWC3 revision < 2.20a have an issue
+ * which would cause metastability state on Run/Stop
+ * bit if we try to force the IP to USB2-only mode.
+ *
+ * Because of that, we check if we hit that issue and
+ * reset core and retry if we did.
+ *
+ * We only attempt this workaround if we are in
+ * DEVICE mode (i.e. not OTG).
+ *
+ * Refers to:
+ *
+ * STAR#9000525659: Clock Domain Crossing on DCTL in
+ * USB 2.0 Mode
+ */
+ if (is_on && dwc->revision < DWC3_REVISION_220A &&
+ dwc->prtcap_mode == DWC3_GCTL_PRTCAP_DEVICE) {
+ u32 devspd, ltssm;
+ unsigned long t;
+
+ /* only applicable if devspd != SUPERSPEED */
+ devspd = dwc3_readl(dwc->regs, DWC3_DCFG) & DWC3_DCFG_SPEED_MASK;
+ if (devspd == DWC3_DCFG_SUPERSPEED)
+ goto done;
+
+ /* get link state */
+ ltssm = dwc3_readl(dwc->regs, DWC3_GDBGLTSSM);
+ ltssm = (ltssm >> 22) & 0xf;
+
+ /**
+ * Need to wait for 100ms and check if ltssm != 4 to detect
+ * metastability issue. If we got a reset event then we are
+ * safe and can continue.
+ */
+ t = wait_for_completion_timeout(&dwc->reset_event,
+ msecs_to_jiffies(100));
+ if (t)
+ goto done;
+
+ /**
+ * If link state != 4 we've hit the metastability issue, soft reset.
+ */
+ if (ltssm == 4)
+ goto done;
+
+ dwc3_trace(trace_dwc3_gadget,
+ "applying metastability workaround\n");
+ trys++;
+ if (trys == 2) {
+ dev_WARN_ONCE(dwc->dev, true,
+ "metastability workaround failed!\n");
+ return -ETIMEDOUT;
+ }
+
+ spin_lock_irqsave(&dwc->lock, flags);
+ /* stop gadget */
+ dwc3_gadget_disable_irq(dwc);
+ __dwc3_gadget_ep_disable(dwc->eps[0]);
+ __dwc3_gadget_ep_disable(dwc->eps[1]);
+
+ /* soft reset device and restart */
+ ret = dwc3_device_reinit(dwc);
+ if (ret) {
+ dev_err(dwc->dev, "device reinit failed\n");
+ return ret;
+ }
+
+ reinit_completion(&dwc->reset_event);
+ /* restart gadget */
+ ret = dwc3_gadget_restart(dwc);
+ if (ret) {
+ dev_err(dwc->dev, "failed to re-init gadget\n");
+ return ret;
+ }
+
+ spin_unlock_irqrestore(&dwc->lock, flags);
+ goto try;
+ }
+
+done:
+
return ret;
}
@@ -1607,37 +1697,12 @@ static void dwc3_gadget_disable_irq(struct dwc3 *dwc)
static irqreturn_t dwc3_interrupt(int irq, void *_dwc);
static irqreturn_t dwc3_thread_interrupt(int irq, void *_dwc);
-static int dwc3_gadget_start(struct usb_gadget *g,
- struct usb_gadget_driver *driver)
+static int dwc3_gadget_restart(struct dwc3 *dwc)
{
- struct dwc3 *dwc = gadget_to_dwc(g);
struct dwc3_ep *dep;
- unsigned long flags;
int ret = 0;
- int irq;
u32 reg;
- irq = platform_get_irq(to_platform_device(dwc->dev), 0);
- ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
- IRQF_SHARED, "dwc3", dwc);
- if (ret) {
- dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
- irq, ret);
- goto err0;
- }
-
- spin_lock_irqsave(&dwc->lock, flags);
-
- if (dwc->gadget_driver) {
- dev_err(dwc->dev, "%s is already bound to %s\n",
- dwc->gadget.name,
- dwc->gadget_driver->driver.name);
- ret = -EBUSY;
- goto err1;
- }
-
- dwc->gadget_driver = driver;
-
reg = dwc3_readl(dwc->regs, DWC3_DCFG);
reg &= ~(DWC3_DCFG_SPEED_MASK);
@@ -1649,12 +1714,15 @@ static int dwc3_gadget_start(struct usb_gadget *g,
* Because of that, we cannot configure the IP to any
* speed other than the SuperSpeed
*
+ * For non OTG mode we can attempt softreset workaround.
+ *
* Refers to:
*
* STAR#9000525659: Clock Domain Crossing on DCTL in
* USB 2.0 Mode
*/
- if (dwc->revision < DWC3_REVISION_220A) {
+ if ((dwc->revision < DWC3_REVISION_220A) &&
+ (dwc->prtcap_mode == DWC3_GCTL_PRTCAP_OTG)) {
reg |= DWC3_DCFG_SUPERSPEED;
} else {
switch (dwc->maximum_speed) {
@@ -1689,7 +1757,7 @@ static int dwc3_gadget_start(struct usb_gadget *g,
false);
if (ret) {
dev_err(dwc->dev, "failed to enable %s\n", dep->name);
- goto err2;
+ return ret;
}
dep = dwc->eps[1];
@@ -1697,7 +1765,7 @@ static int dwc3_gadget_start(struct usb_gadget *g,
false);
if (ret) {
dev_err(dwc->dev, "failed to enable %s\n", dep->name);
- goto err3;
+ goto err;
}
/* begin to receive SETUP packets */
@@ -1706,12 +1774,50 @@ static int dwc3_gadget_start(struct usb_gadget *g,
dwc3_gadget_enable_irq(dwc);
- spin_unlock_irqrestore(&dwc->lock, flags);
-
return 0;
-err3:
+err:
__dwc3_gadget_ep_disable(dwc->eps[0]);
+ return ret;
+}
+
+static int dwc3_gadget_start(struct usb_gadget *g,
+ struct usb_gadget_driver *driver)
+{
+ struct dwc3 *dwc = gadget_to_dwc(g);
+ unsigned long flags;
+ int ret = 0;
+ int irq;
+
+ irq = platform_get_irq(to_platform_device(dwc->dev), 0);
+ ret = request_threaded_irq(irq, dwc3_interrupt, dwc3_thread_interrupt,
+ IRQF_SHARED, "dwc3", dwc);
+ if (ret) {
+ dev_err(dwc->dev, "failed to request irq #%d --> %d\n",
+ irq, ret);
+ goto err0;
+ }
+
+ spin_lock_irqsave(&dwc->lock, flags);
+
+ if (dwc->gadget_driver) {
+ dev_err(dwc->dev, "%s is already bound to %s\n",
+ dwc->gadget.name,
+ dwc->gadget_driver->driver.name);
+ ret = -EBUSY;
+ goto err1;
+ }
+
+ dwc->gadget_driver = driver;
+
+ ret = dwc3_gadget_restart(dwc);
+ if (ret) {
+ dev_err(dwc->dev, "gadget start failed\n");
+ goto err2;
+ }
+
+ spin_unlock_irqrestore(&dwc->lock, flags);
+ return 0;
err2:
dwc->gadget_driver = NULL;
@@ -2321,6 +2427,9 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
dwc3_gadget_disconnect_interrupt(dwc);
}
+ /* notify run/stop metastability workaround */
+ complete(&dwc->reset_event);
+
dwc3_reset_gadget(dwc);
reg = dwc3_readl(dwc->regs, DWC3_DCTL);
@@ -2868,6 +2977,8 @@ int dwc3_gadget_init(struct dwc3 *dwc)
*/
dwc->gadget.quirk_ep_out_aligned_size = true;
+ init_completion(&dwc->reset_event);
+
/*
* REVISIT: Here we should clear all pending IRQs to be
* sure we're starting from a well known location.
--
2.5.0
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