diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index a2587f9f0bb8..517aa7f1486d 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -425,8 +425,7 @@ static void dwc3_ref_clk_period(struct dwc3 *dwc)
 	}
 
 	reg = dwc3_readl(dwc, DWC3_GUCTL);
-	reg &= ~DWC3_GUCTL_REFCLKPER_MASK;
-	reg |=  FIELD_PREP(DWC3_GUCTL_REFCLKPER_MASK, period);
+	FIELD_MODIFY(DWC3_GUCTL_REFCLKPER_MASK, &reg, period);
 	dwc3_writel(dwc, DWC3_GUCTL, reg);
 
 	if (DWC3_VER_IS_PRIOR(DWC3, 250A))
@@ -456,12 +455,9 @@ static void dwc3_ref_clk_period(struct dwc3 *dwc)
 	decr = 480000000 / rate;
 
 	reg = dwc3_readl(dwc, DWC3_GFLADJ);
-	reg &= ~DWC3_GFLADJ_REFCLK_FLADJ_MASK
-	    &  ~DWC3_GFLADJ_240MHZDECR
-	    &  ~DWC3_GFLADJ_240MHZDECR_PLS1;
-	reg |= FIELD_PREP(DWC3_GFLADJ_REFCLK_FLADJ_MASK, fladj)
-	    |  FIELD_PREP(DWC3_GFLADJ_240MHZDECR, decr >> 1)
-	    |  FIELD_PREP(DWC3_GFLADJ_240MHZDECR_PLS1, decr & 1);
+	FIELD_MODIFY(DWC3_GFLADJ_REFCLK_FLADJ_MASK, &reg, fladj);
+	FIELD_MODIFY(DWC3_GFLADJ_240MHZDECR, &reg, decr >> 1);
+	FIELD_MODIFY(DWC3_GFLADJ_240MHZDECR_PLS1, &reg, decr & 1);
 
 	if (dwc->gfladj_refclk_lpm_sel)
 		reg |=  DWC3_GFLADJ_REFCLK_LPM_SEL;