Revert "usb: dwc2: Move reset into dwc2_get_hwparams()"

This reverts commit 263b7fb557f7 ("usb: dwc2: Move reset into
dwc2_get_hwparams()") due to regression found on bcm2835 platform. USB
ethernet fails, due to being unable to pick up proper parameters when
performing a plain reset before reading hw params.

Below shows the results of the gnptxfsiz and hptxfsiz with and before
and after reverting this (from Stefan Wahren):

So here is the probe result before Patch 1 is applied:

[    1.283148] dwc2 20980000.usb: Configuration mismatch. dr_mode forced to host
[    1.313894] dwc2 20980000.usb: gnptxfsiz=00201000
[    1.314104] dwc2 20980000.usb: hptxfsiz=00000000
[    1.353908] dwc2 20980000.usb: 256 invalid for host_nperio_tx_fifo_size. Check HW configuration.
[    1.354262] dwc2 20980000.usb: 512 invalid for host_perio_tx_fifo_size. Check HW configuration.
[    1.394249] dwc2 20980000.usb: DWC OTG Controller
[    1.394561] dwc2 20980000.usb: new USB bus registered, assigned bus number 1
[    1.394917] dwc2 20980000.usb: irq 33, io mem 0x00000000

And here is the probe result after Patch 1 is applied:

[    1.280107] dwc2 20980000.usb: Configuration mismatch. dr_mode forced to host
[    1.353949] dwc2 20980000.usb: gnptxfsiz=01001000
[    1.354166] dwc2 20980000.usb: hptxfsiz=02002000
[    1.434301] dwc2 20980000.usb: DWC OTG Controller
[    1.434616] dwc2 20980000.usb: new USB bus registered, assigned bus number 1
[    1.434973] dwc2 20980000.usb: irq 33, io mem 0x00000000

Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Reported-by: Stefan Wahren <stefan.wahren@i2se.com>
Reported-by: Remi Pommarel <repk@triplefau.lt>
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Tested-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/dwc2/core.c

@@ -3278,9 +3278,6 @@ static void dwc2_get_dev_hwparams(struct dwc2_hsotg *hsotg)
 /**
  * During device initialization, read various hardware configuration
  * registers and interpret the contents.
- *
- * This should be called during driver probe. It will perform a core
- * soft reset in order to get the reset values of the parameters.
  */
 int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 {
@@ -3288,7 +3285,6 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 	unsigned width;
 	u32 hwcfg1, hwcfg2, hwcfg3, hwcfg4;
 	u32 grxfsiz;
-	int retval;
 
 	/*
 	 * Attempt to ensure this device is really a DWC_otg Controller.
@@ -3308,10 +3304,6 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
 		hw->snpsid >> 12 & 0xf, hw->snpsid >> 8 & 0xf,
 		hw->snpsid >> 4 & 0xf, hw->snpsid & 0xf, hw->snpsid);
 
-	retval = dwc2_core_reset(hsotg);
-	if (retval)
-		return retval;
-
 	hwcfg1 = dwc2_readl(hsotg->regs + GHWCFG1);
 	hwcfg2 = dwc2_readl(hsotg->regs + GHWCFG2);
 	hwcfg3 = dwc2_readl(hsotg->regs + GHWCFG3);

drivers/usb/dwc2/platform.c

@@ -530,7 +530,13 @@ static int dwc2_driver_probe(struct platform_device *dev)
 	if (retval)
 		return retval;
 
-	/* Reset the controller and detect hardware config values */
+	/*
+	 * Reset before dwc2_get_hwparams() then it could get power-on real
+	 * reset value form registers.
+	 */
+	dwc2_core_reset_and_force_dr_mode(hsotg);
+
+	/* Detect config values from hardware */
 	retval = dwc2_get_hwparams(hsotg);
 	if (retval)
 		goto error;