[PATCH 1/4] usb: dwc3: gadget: Don't send unintended link state change

[Thinh Nguyen]

DCTL.ULSTCHNGREQ is a write-only field. When doing a read-modify-write
to DCTL, the driver must make sure that there's no unintended link state
change request from whatever is read from DCTL.ULSTCHNGREQ. Set link
state change to no-action when the driver writes to DCTL.

Signed-off-by: Thinh Nguyen <thi...@synopsys.com>
---
 drivers/usb/dwc3/gadget.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 86dc1db788a9..24178b4b9d46 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -57,6 +57,8 @@ int dwc3_gadget_set_test_mode(struct dwc3 *dwc, int mode)
                return -EINVAL;
        }
 
+       /* Don't send link state change request */
+       reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
 
        return 0;
@@ -1822,6 +1824,9 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int 
is_on, int suspend)
                dwc->pullups_connected = false;
        }
 
+       /* Don't send link state change request */
+       reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
+
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
 
        do {
@@ -2744,6 +2749,10 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 
*dwc)
        int                     reg;
 
        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
+
+       /* Don't send link state change request */
+       reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
+
        reg &= ~DWC3_DCTL_INITU1ENA;
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
 
@@ -2799,6 +2808,10 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
        dwc3_reset_gadget(dwc);
 
        reg = dwc3_readl(dwc->regs, DWC3_DCTL);
+
+       /* Don't send link state change request */
+       reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
+
        reg &= ~DWC3_DCTL_TSTCTRL_MASK;
        dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        dwc->test_mode = false;
@@ -2904,10 +2917,15 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 
*dwc)
                if (dwc->has_lpm_erratum && dwc->revision >= DWC3_REVISION_240A)
                        reg |= DWC3_DCTL_NYET_THRES(dwc->lpm_nyet_threshold);
 
+               /* Don't send link state change request */
+               reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        } else {
                reg = dwc3_readl(dwc->regs, DWC3_DCTL);
                reg &= ~DWC3_DCTL_HIRD_THRES_MASK;
+
+               /* Don't send link state change request */
+               reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
        }
 
@@ -3017,6 +3035,9 @@ static void dwc3_gadget_linksts_change_interrupt(struct 
dwc3 *dwc,
 
                                reg &= ~u1u2;
 
+                               /* Don't send link state change request */
+                               reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
+
                                dwc3_writel(dwc->regs, DWC3_DCTL, reg);
                                break;
                        default:
-- 
2.11.0