When a FS device is following a suspend-reset-enumeration-data
transfer sequence, sometimes it goes back in suspend just after reset
without the link entering L0. This is seen in only when the following
scenarios are met:
- SOF and EOR happens at the same clock cycle
- UTMI line state should transition from SE0 to K at the same clock
cycle(if the UTMI line state transition from SE0 to J at the same
clock cycle then problem is not seen)
Attemting a power cycle of the root hub recovers the problem described.
To identify the issue, PLS goes to disabled state followed by CSC bit
being set(because of CCS status change).
Signed-off-by: Pratham Pratap <quic_ppratap@xxxxxxxxxxx>
---
v1:
Problem is seen on core emulation setup with eUSB2 PHY test chip.
This failure is seen only in full speed host mode usecase with all
available eUSB2 repeater randomly in 1 out of 5000 to 6000 iterations.
As of now, we don't have any SOC with eUSB2 PHY on which this fix can
be tested.
drivers/usb/core/hub.c | 34 ++++++++++++++++++++++++++--------
drivers/usb/host/xhci-plat.c | 3 +++
include/linux/usb/hcd.h | 1 +
include/uapi/linux/usb/ch11.h | 1 +
4 files changed, 31 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 47a1c8b..6a65092 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2834,10 +2834,20 @@ static bool hub_port_warm_reset_required(struct usb_hub *hub, int port1,
|| link_state == USB_SS_PORT_LS_COMP_MOD;
}
+static void usb_hub_port_power_cycle(struct usb_device *hdev, struct usb_hub *hub, int port1)
+{
+ dev_info(&hub->ports[port1 - 1]->dev, "attempt power cycle\n");
+ usb_hub_set_port_power(hdev, hub, port1, false);
+ msleep(2 * hub_power_on_good_delay(hub));
+ usb_hub_set_port_power(hdev, hub, port1, true);
+ msleep(hub_power_on_good_delay(hub));
+}
+
static int hub_port_wait_reset(struct usb_hub *hub, int port1,
struct usb_device *udev, unsigned int delay, bool warm)
{
int delay_time, ret;
+ struct usb_hcd *hcd = bus_to_hcd(udev->bus);
u16 portstatus;
u16 portchange;
u32 ext_portstatus = 0;
@@ -2887,8 +2897,21 @@ static int hub_port_wait_reset(struct usb_hub *hub, int port1,
return -ENOTCONN;
/* Device went away? */
- if (!(portstatus & USB_PORT_STAT_CONNECTION))
+ if (!(portstatus & USB_PORT_STAT_CONNECTION)) {
+ /*
+ * When a FS device is following a suspend-reset-enumeration-data_transfer
+ * sequence, sometimes it goes back in suspend just after reset without the
+ * link entering L0. To fix this when CSC bit is set(because of CCS status
+ * change) power cycle the root hub.
+ */
+ if (udev->reset_resume && (!udev->parent && hcd->fs_suspend_reset) &&
+ (portstatus & USB_PORT_STAT_CSC)) {
+ usb_hub_port_power_cycle(hdev, hub, port1);
+ return -EAGAIN;
+ }
+
return -ENOTCONN;
+ }
/* Retry if connect change is set but status is still connected.
* A USB 3.0 connection may bounce if multiple warm resets were issued,
@@ -5393,13 +5416,8 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus,
break;
/* When halfway through our retry count, power-cycle the port */
- if (i == (PORT_INIT_TRIES - 1) / 2) {
- dev_info(&port_dev->dev, "attempt power cycle\n");
- usb_hub_set_port_power(hdev, hub, port1, false);
- msleep(2 * hub_power_on_good_delay(hub));
- usb_hub_set_port_power(hdev, hub, port1, true);
- msleep(hub_power_on_good_delay(hub));
- }
+ if (i == (PORT_INIT_TRIES - 1) / 2)
+ usb_hub_port_power_cycle(hdev, hub, port1);
}
if (hub->hdev->parent ||
!hcd->driver->port_handed_over ||
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index c1edcc9..607c4f0 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -342,6 +342,9 @@ static int xhci_plat_probe(struct platform_device *pdev)
hcd->tpl_support = of_usb_host_tpl_support(sysdev->of_node);
xhci->shared_hcd->tpl_support = hcd->tpl_support;
+ hcd->fs_suspend_reset = of_property_read_bool(sysdev->of_node, "fs-suspend-reset");
+ xhci->shared_hcd->fs_suspend_reset = hcd->fs_suspend_reset;
+
if (priv) {
ret = xhci_priv_plat_setup(hcd);
if (ret)
diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h
index 548a028..05ccbc8 100644
--- a/include/linux/usb/hcd.h
+++ b/include/linux/usb/hcd.h
@@ -172,6 +172,7 @@ struct usb_hcd {
unsigned tpl_support:1; /* OTG & EH TPL support */
unsigned cant_recv_wakeups:1;
/* wakeup requests from downstream aren't received */
+ unsigned fs_suspend_reset:1; /* fs suspend reset bug */
unsigned int irq; /* irq allocated */
void __iomem *regs; /* device memory/io */
diff --git a/include/uapi/linux/usb/ch11.h b/include/uapi/linux/usb/ch11.h
index fb0cd24..576bbf9 100644
--- a/include/uapi/linux/usb/ch11.h
+++ b/include/uapi/linux/usb/ch11.h
@@ -135,6 +135,7 @@ struct usb_port_status {
#define USB_PORT_STAT_TEST 0x0800
#define USB_PORT_STAT_INDICATOR 0x1000
/* bits 13 to 15 are reserved */
+#define USB_PORT_STAT_CSC 0x20000
/*
* Additions to wPortStatus bit field from USB 3.0
--
2.7.4
