[PATCH 2/6] usb: dwc3: gadget: clear SUSPHY bit before ep cmds

[A. Sverdlin]

From: Felipe Balbi <felipe.ba...@linux.intel.com>

Upstream Linux commit 2b0f11df84bb.

Synopsys Databook 2.60a has a note that if we're
sending an endpoint command we _must_ make sure that
DWC3_GUSB2PHY(n).SUSPHY bit is cleared.

This patch implements that particular detail.

Signed-off-by: Felipe Balbi <felipe.ba...@linux.intel.com>
Signed-off-by: Alexander Sverdlin <alexander.sverd...@siemens.com>
---
 drivers/usb/dwc3/gadget.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 17c19285f1c24..8f6513752f085 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -302,8 +302,25 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
 {
        u32                     timeout = 500;
        u32                     reg;
+
+       int                     susphy = false;
        int                     ret = -EINVAL;
 
+       /*
+        * Synopsys Databook 2.60a states, on section 6.3.2.5.[1-8], that if
+        * we're issuing an endpoint command, we must check if
+        * GUSB2PHYCFG.SUSPHY bit is set. If it is, then we need to clear it.
+        *
+        * We will also set SUSPHY bit to what it was before returning as stated
+        * by the same section on Synopsys databook.
+        */
+       reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
+       if (unlikely(reg & DWC3_GUSB2PHYCFG_SUSPHY)) {
+               susphy = true;
+               reg &= ~DWC3_GUSB2PHYCFG_SUSPHY;
+               dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
+       }
+
        dwc3_writel(dwc->regs, DWC3_DEPCMDPAR0(ep), params->param0);
        dwc3_writel(dwc->regs, DWC3_DEPCMDPAR1(ep), params->param1);
        dwc3_writel(dwc->regs, DWC3_DEPCMDPAR2(ep), params->param2);
@@ -331,6 +348,12 @@ int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
                udelay(1);
        } while (1);
 
+       if (unlikely(susphy)) {
+               reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
+               reg |= DWC3_GUSB2PHYCFG_SUSPHY;
+               dwc3_writel(dwc->regs, DWC3_GUSB2PHYCFG(0), reg);
+       }
+
        return ret;
 }
 
-- 
2.44.0