[PATCH v1 4/8] usb: dwc3: core: do not use 3.0 clock when operating in 2.0 mode

[Peter Geis <pgwipeout@gmail.com>]

From: Bin Yang <yangbin@rock-chips.com>

In the 3.0 device core, if the core is programmed to operate in
2.0 only, then setting the GUCTL1.DEV_FORCE_20_CLK_FOR_30_CLK makes
the internal 2.0(utmi/ulpi) clock to be routed as the 3.0 (pipe)
clock. Enabling this feature allows the pipe3 clock to be not-running
when forcibly operating in 2.0 device mode.

Signed-off-by: Bin Yang <yangbin@rock-chips.com>
Signed-off-by: Peter Geis <pgwipeout@gmail.com>
---
 drivers/usb/dwc3/core.c | 4 ++++
 drivers/usb/dwc3/core.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 18adddfba3da..032d40794fae 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1167,6 +1167,10 @@ static int dwc3_core_init(struct dwc3 *dwc)
 		if (dwc->parkmode_disable_ss_quirk)
 			reg |= DWC3_GUCTL1_PARKMODE_DISABLE_SS;
 
+		if (dwc->maximum_speed == USB_SPEED_HIGH ||
+		    dwc->maximum_speed == USB_SPEED_FULL)
+			reg |= DWC3_GUCTL1_DEV_FORCE_20_CLK_FOR_30_CLK;
+
 		dwc3_writel(dwc->regs, DWC3_GUCTL1, reg);
 	}
 
diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index eb9c1efced05..ea3ca04406bb 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -259,6 +259,7 @@
 /* Global User Control 1 Register */
 #define DWC3_GUCTL1_DEV_DECOUPLE_L1L2_EVT	BIT(31)
 #define DWC3_GUCTL1_TX_IPGAP_LINECHECK_DIS	BIT(28)
+#define DWC3_GUCTL1_DEV_FORCE_20_CLK_FOR_30_CLK	BIT(26)
 #define DWC3_GUCTL1_DEV_L1_EXIT_BY_HW		BIT(24)
 #define DWC3_GUCTL1_PARKMODE_DISABLE_SS		BIT(17)
 
-- 
2.25.1