usb: dwc3: gadget: Check for disabled LPM quirk

If the device doesn't support LPM, make sure to disable the LPM
capability and don't advertise to the host that it supports it.
Acked-by: NFelipe Balbi <balbi@kernel.org>
Signed-off-by: NThinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/9e68527ff932b1646f92a7593d4092a903754666.1618366071.git.Thinh.Nguyen@synopsys.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/core.c

@@ -1286,6 +1286,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
 				"snps,usb3_lpm_capable");
 	dwc->usb2_lpm_disable = device_property_read_bool(dev,
 				"snps,usb2-lpm-disable");
+	dwc->usb2_gadget_lpm_disable = device_property_read_bool(dev,
+				"snps,usb2-gadget-lpm-disable");
 	device_property_read_u8(dev, "snps,rx-thr-num-pkt-prd",
 				&rx_thr_num_pkt_prd);
 	device_property_read_u8(dev, "snps,rx-max-burst-prd",

drivers/usb/dwc3/core.h

@@ -1036,7 +1036,8 @@ struct dwc3_scratchpad_array {
  * @dis_start_transfer_quirk: set if start_transfer failure SW workaround is
  *			not needed for DWC_usb31 version 1.70a-ea06 and below
  * @usb3_lpm_capable: set if hadrware supports Link Power Management
- * @usb2_lpm_disable: set to disable usb2 lpm
+ * @usb2_lpm_disable: set to disable usb2 lpm for host
+ * @usb2_gadget_lpm_disable: set to disable usb2 lpm for gadget
  * @disable_scramble_quirk: set if we enable the disable scramble quirk
  * @u2exit_lfps_quirk: set if we enable u2exit lfps quirk
  * @u2ss_inp3_quirk: set if we enable P3 OK for U2/SS Inactive quirk
@@ -1242,6 +1243,7 @@ struct dwc3 {
 	unsigned		dis_start_transfer_quirk:1;
 	unsigned		usb3_lpm_capable:1;
 	unsigned		usb2_lpm_disable:1;
+	unsigned		usb2_gadget_lpm_disable:1;
 
 	unsigned		disable_scramble_quirk:1;
 	unsigned		u2exit_lfps_quirk:1;

drivers/usb/dwc3/gadget.c

@@ -3495,6 +3495,7 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
 	/* Enable USB2 LPM Capability */
 
 	if (!DWC3_VER_IS_WITHIN(DWC3, ANY, 194A) &&
+	    !dwc->usb2_gadget_lpm_disable &&
 	    (speed != DWC3_DSTS_SUPERSPEED) &&
 	    (speed != DWC3_DSTS_SUPERSPEED_PLUS)) {
 		reg = dwc3_readl(dwc->regs, DWC3_DCFG);
@@ -3521,6 +3522,12 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
 
 		dwc3_gadget_dctl_write_safe(dwc, reg);
 	} else {
+		if (dwc->usb2_gadget_lpm_disable) {
+			reg = dwc3_readl(dwc->regs, DWC3_DCFG);
+			reg &= ~DWC3_DCFG_LPM_CAP;
+			dwc3_writel(dwc->regs, DWC3_DCFG, reg);
+		}
+
 		reg = dwc3_readl(dwc->regs, DWC3_DCTL);
 		reg &= ~DWC3_DCTL_HIRD_THRES_MASK;
 		dwc3_gadget_dctl_write_safe(dwc, reg);
@@ -3969,7 +3976,7 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 	dwc->gadget->ssp_rate		= USB_SSP_GEN_UNKNOWN;
 	dwc->gadget->sg_supported	= true;
 	dwc->gadget->name		= "dwc3-gadget";
-	dwc->gadget->lpm_capable	= true;
+	dwc->gadget->lpm_capable	= !dwc->usb2_gadget_lpm_disable;
 
 	/*
 	 * FIXME We might be setting max_speed to <SUPER, however versions