When DWC3 is set to host mode by programming register DWC3_GCTL, VUBS
(or its control signal) will be turned on immediately on related Root Hub
ports. Then, the VUBS is turned off for a little while(15us) when do xhci
reset (conducted by xhci driver) and back to normal finally, we can
observed a negative glitch of related signal from scope.
This VBUS glitch might cause some USB devices enumeration fail if kernel
boot with them connected. Such as LS1012AFWRY/LS1043ARDB/LX2160AQDS
/LS1088ARDB with Kingston 16GB USB2.0/Kingston USB3.0/JetFlash Transcend
4GB USB2.0 drives. The fail cases include enumerated as full-speed device
or report wrong device descriptor, etc.
One SW workaround which can fix this is to program all xhci PORTSC[PP]
to 0 to turn off VBUS immediately after setting host mode in DWC3 driver
(per signal measurement result, it will be too late to do it in
xhci-plat.c or xhci.c). Then, after xhci reset complete in xhci driver,
PORTSC[PP]s' value will back to 1 automatically and VBUS on at that time,
no glitch happen and normal enumeration process has no impact.
Signed-off-by: Ran Wang <ran.wang_1@xxxxxxx>
---
drivers/usb/dwc3/core.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
drivers/usb/dwc3/core.h | 10 +++++++++-
2 files changed, 56 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index a1b126f..1508397 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -100,6 +100,41 @@ static int dwc3_get_dr_mode(struct dwc3 *dwc)
return 0;
}
+/*
+ * dwc3_power_of_all_roothub_ports - Power off all Root hub ports
+ * @dwc3: Pointer to our controller context structure
+ */
+static void dwc3_power_off_all_roothub_ports(struct dwc3 *dwc)
+{
+ int i, port_num;
+ u32 reg, op_regs_base, offset;
+ void __iomem *xhci_regs;
+
+ /* xhci regs is not mapped yet, do it temperary here */
+ if (dwc->xhci_resources[0].start) {
+ xhci_regs = ioremap(dwc->xhci_resources[0].start,
+ DWC3_XHCI_REGS_END);
+ if (IS_ERR(xhci_regs)) {
+ dev_err(dwc->dev, "Failed to ioremap xhci_regs\n");
+ return;
+ }
+
+ op_regs_base = HC_LENGTH(readl(xhci_regs));
+ reg = readl(xhci_regs + XHCI_HCSPARAMS1);
+ port_num = HCS_MAX_PORTS(reg);
+
+ for (i = 1; i <= port_num; i++) {
+ offset = op_regs_base + XHCI_PORTSC_BASE + 0x10*(i-1);
+ reg = readl(xhci_regs + offset);
+ reg &= ~PORT_POWER;
+ writel(reg, xhci_regs + offset);
+ }
+
+ iounmap(xhci_regs);
+ } else
+ dev_err(dwc->dev, "xhci base reg invalid\n");
+}
+
void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
{
u32 reg;
@@ -109,6 +144,15 @@ void dwc3_set_prtcap(struct dwc3 *dwc, u32 mode)
reg |= DWC3_GCTL_PRTCAPDIR(mode);
dwc3_writel(dwc->regs, DWC3_GCTL, reg);
+ /*
+ * We have to power off all Root hub ports immediately after DWC3 set
+ * to host mode to avoid VBUS glitch happen when xhci get reset later.
+ */
+ if (dwc->avoid_vbus_glitch_when_set_host) {
+ if (mode == DWC3_GCTL_PRTCAP_HOST)
+ dwc3_power_off_all_roothub_ports(dwc);
+ }
+
dwc->current_dr_role = mode;
}
@@ -1306,6 +1350,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
dwc->dis_metastability_quirk = device_property_read_bool(dev,
"snps,dis_metastability_quirk");
+ dwc->avoid_vbus_glitch_when_set_host = device_property_read_bool(dev,
+ "snps,avoid-vbus-glitch-when-set-host");
+
dwc->lpm_nyet_threshold = lpm_nyet_threshold;
dwc->tx_de_emphasis = tx_de_emphasis;
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index df87641..691093b 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -606,6 +606,14 @@
#define DWC3_OSTS_VBUSVLD BIT(1)
#define DWC3_OSTS_CONIDSTS BIT(0)
+/* Partial XHCI Register and Bit fields for quirk */
+#define XHCI_HCSPARAMS1 0x4
+#define XHCI_PORTSC_BASE 0x400
+#define PORT_POWER (1 << 9)
+#define HCS_MAX_PORTS(p) (((p) >> 24) & 0x7f)
+#define XHCI_HC_LENGTH(p) (((p)>>00)&0x00ff)
+#define HC_LENGTH(p) XHCI_HC_LENGTH(p)
+
/* Structures */
struct dwc3_trb;
@@ -1209,6 +1217,7 @@ struct dwc3 {
unsigned tx_de_emphasis:2;
unsigned dis_metastability_quirk:1;
+ unsigned avoid_vbus_glitch_when_set_host:1;
u16 imod_interval;
};
@@ -1217,7 +1226,6 @@ struct dwc3 {
#define INCRX_UNDEF_LENGTH_BURST_MODE 1
#define work_to_dwc(w) (container_of((w), struct dwc3, drd_work))
-
/* -------------------------------------------------------------------------- */
struct dwc3_event_type {
--
1.7.1
