usb: dwc3: Allow disabling of metastability workaround
Some platforms (e.g. TI's DRA7 USB2 instance) have more trouble
with the metastability workaround as it supports only
a High-Speed PHY and the PHY can enter into an Erratic state [1]
when the controller is set in SuperSpeed mode as part of
the metastability workaround.
This causes upto 2 seconds delay in enumeration on DRA7's USB2
instance in gadget mode.
If these platforms can be better off without the workaround,
provide a device tree property to suggest that so the workaround
is avoided.
[1] Device mode enumeration trace showing PHY Erratic Error.
irq/90-dwc3-969 [000] d... 52.323145: dwc3_event: event (00000901): Erratic Error [U0]
irq/90-dwc3-969 [000] d... 52.560646: dwc3_event: event (00000901): Erratic Error [U0]
irq/90-dwc3-969 [000] d... 52.798144: dwc3_event: event (00000901): Erratic Error [U0]
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 0783250..c32d2b9 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1062,6 +1062,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
device_property_read_u32(dev, "snps,quirk-frame-length-adjustment",
&dwc->fladj);
+ dwc->dis_metastability_quirk = device_property_read_bool(dev,
+ "snps,dis_metastability_quirk");
+
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 be60d79..03c7aaa 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -856,6 +856,7 @@ struct dwc3_scratchpad_array {
* 1 - -3.5dB de-emphasis
* 2 - No de-emphasis
* 3 - Reserved
+ * @dis_metastability_quirk: set to disable metastability quirk.
* @imod_interval: set the interrupt moderation interval in 250ns
* increments or 0 to disable.
*/
@@ -1008,6 +1009,8 @@ struct dwc3 {
unsigned tx_de_emphasis_quirk:1;
unsigned tx_de_emphasis:2;
+ unsigned dis_metastability_quirk:1;
+
u16 imod_interval;
};
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 981fd98..2168ba4 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2005,7 +2005,8 @@ static void dwc3_gadget_set_speed(struct usb_gadget *g,
* 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->dis_metastability_quirk) {
reg |= DWC3_DCFG_SUPERSPEED;
} else {
switch (speed) {
@@ -3224,7 +3225,8 @@ int dwc3_gadget_init(struct dwc3 *dwc)
* is less than super speed because we don't have means, yet, to tell
* composite.c that we are USB 2.0 + LPM ECN.
*/
- if (dwc->revision < DWC3_REVISION_220A)
+ if (dwc->revision < DWC3_REVISION_220A &&
+ !dwc->dis_metastability_quirk)
dev_info(dwc->dev, "changing max_speed on rev %08x\n",
dwc->revision);