diff --git a/grub-core/bus/usb/ehci.c b/grub-core/bus/usb/ehci.c
index fe5cf6eb8..3421d630c 100644
--- a/grub-core/bus/usb/ehci.c
+++ b/grub-core/bus/usb/ehci.c
@@ -405,18 +405,14 @@ grub_ehci_port_setbits (struct grub_ehci *e, grub_uint32_t port,
 static inline void *
 grub_ehci_phys2virt (grub_uint32_t phys, struct grub_pci_dma_chunk *chunk)
 {
-  if (!phys)
-    return NULL;
-  return (void *) (phys - grub_dma_get_phys (chunk)
-		   + (grub_uint32_t) grub_dma_get_virt (chunk));
+  return ((grub_uint8_t *) grub_dma_get_virt (chunk)
+	  + (phys - grub_dma_get_phys (chunk)));
 }
 
 static inline grub_uint32_t
 grub_ehci_virt2phys (volatile void *virt, struct grub_pci_dma_chunk *chunk)
 {
-  if (!virt)
-    return 0;
-  return ((grub_uint32_t) virt - (grub_uint32_t) grub_dma_get_virt (chunk)
+  return (((grub_uint8_t *) virt - (grub_uint8_t *) grub_dma_get_virt (chunk))
 	  + grub_dma_get_phys (chunk));
 }
 
@@ -666,7 +662,7 @@ grub_ehci_pci_iter (grub_pci_device_t dev,
   for (i = 1; i < GRUB_EHCI_N_QH; i++)
     {
       e->qh_virt[i].qh_hptr =
-	grub_cpu_to_le32 ((grub_ehci_virt2phys ((void *) &e->qh_virt[i],
+	grub_cpu_to_le32 ((grub_ehci_virt2phys (&e->qh_virt[i],
 						e->qh_chunk) &
 			   GRUB_EHCI_POINTER_MASK) | GRUB_EHCI_HPTR_TYPE_QH);
       e->qh_virt[i].td_overlay.next_td =
@@ -758,7 +754,7 @@ grub_ehci_pci_iter (grub_pci_device_t dev,
   /* Setup list address registers */
   grub_ehci_oper_write32 (e, GRUB_EHCI_FL_BASE, e->framelist_phys);
   grub_ehci_oper_write32 (e, GRUB_EHCI_CUR_AL_ADDR,
-			  grub_ehci_virt2phys ((void *) &e->qh_virt[1],
+			  grub_ehci_virt2phys (&e->qh_virt[1],
 					       e->qh_chunk));
 
   /* Set ownership of root hub ports to EHCI */
@@ -970,12 +966,11 @@ grub_ehci_find_qh (struct grub_ehci *e, grub_usb_transfer_t transfer)
   grub_ehci_setup_qh (&qh[i], transfer);
   /* Linking - this new (last) QH will point to first QH */
   qh[i].qh_hptr = grub_cpu_to_le32 (GRUB_EHCI_HPTR_TYPE_QH
-				    | grub_ehci_virt2phys ((void *) &qh[1],
+				    | grub_ehci_virt2phys (&qh[1],
 							   e->qh_chunk));
   /* Linking - previous last QH will point to this new QH */
   qh[i - 1].qh_hptr = grub_cpu_to_le32 (GRUB_EHCI_HPTR_TYPE_QH
-					| grub_ehci_virt2phys ((void *)
-							       &qh[i],
+					| grub_ehci_virt2phys (&qh[i],
 							       e->qh_chunk));
 
   return &qh[i];
@@ -995,7 +990,10 @@ grub_ehci_alloc_td (struct grub_ehci *e)
 
   ret = e->tdfree_virt;		/* Take current free TD */
   /* Advance to next free TD in chain */
-  e->tdfree_virt = grub_ehci_phys2virt (ret->link_td, e->td_chunk);
+  if (ret->link_td)
+    e->tdfree_virt = grub_ehci_phys2virt (ret->link_td, e->td_chunk);
+  else
+    e->tdfree_virt = NULL;
   ret->link_td = 0;		/* Reset link_td in allocated TD */
   return ret;
 }
@@ -1004,7 +1002,10 @@ static void
 grub_ehci_free_td (struct grub_ehci *e, grub_ehci_td_t td)
 {
   /* Chain new free TD & rest */
-  td->link_td = grub_ehci_virt2phys (e->tdfree_virt, e->td_chunk);
+  if (e->tdfree_virt)
+    td->link_td = grub_ehci_virt2phys (e->tdfree_virt, e->td_chunk);
+  else
+    td->link_td = 0;
   e->tdfree_virt = td;		/* Change address of first free TD */
 }
 
@@ -1037,7 +1038,10 @@ grub_ehci_free_tds (struct grub_ehci *e, grub_ehci_td_t td,
 
       /* Unlink the TD */
       tdprev = td;
-      td = grub_ehci_phys2virt (td->link_td, e->td_chunk);
+      if (td->link_td)
+	td = grub_ehci_phys2virt (td->link_td, e->td_chunk);
+      else
+	td = NULL;
 
       /* Free the TD.  */
       grub_ehci_free_td (e, tdprev);
@@ -1108,8 +1112,8 @@ grub_ehci_transaction (struct grub_ehci *e,
    * will not be really fetched because it is not active. But don't
    * forget, EHCI will try to fetch alternate TD every scan of AL
    * until QH is halted. */
-  td->alt_next_td =
-    grub_cpu_to_le32 (grub_ehci_virt2phys ((void *) td_alt, e->td_chunk));
+  td->alt_next_td = grub_cpu_to_le32 (grub_ehci_virt2phys (td_alt,
+							   e->td_chunk));
   /* token:
    * TOGGLE - according to toggle
    * TOTAL SIZE = size
@@ -1292,7 +1296,7 @@ grub_ehci_setup_transfer (grub_usb_controller_t dev,
   /* Link new TDs with QH via next_td */
   cdata->qh_virt->td_overlay.next_td =
     grub_cpu_to_le32 (grub_ehci_virt2phys
-		      ((void *) cdata->td_first_virt, e->td_chunk));
+		      (cdata->td_first_virt, e->td_chunk));
   /* Reset Active and Halted bits in QH to activate Advance Queue,
    * i.e. reset token */
   cdata->qh_virt->td_overlay.token = grub_cpu_to_le32 (0);
@@ -1544,7 +1548,7 @@ grub_ehci_cancel_transfer (grub_usb_controller_t dev,
   /* Finaly we should return QH back to the AL... */
   e->qh_virt[i - 1].qh_hptr =
     grub_cpu_to_le32 (grub_ehci_virt2phys
-		      ((void *) cdata->qh_virt, e->qh_chunk));
+		      (cdata->qh_virt, e->qh_chunk));
   grub_free (cdata);
 
   grub_dprintf ("ehci", "cancel_transfer: end\n");
@@ -1741,7 +1745,7 @@ grub_ehci_restore_hw (void)
       /* Setup some EHCI registers and enable EHCI */
       grub_ehci_oper_write32 (e, GRUB_EHCI_FL_BASE, e->framelist_phys);
       grub_ehci_oper_write32 (e, GRUB_EHCI_CUR_AL_ADDR,
-			      grub_ehci_virt2phys ((void *) &e->qh_virt[1],
+			      grub_ehci_virt2phys (&e->qh_virt[1],
 						   e->qh_chunk));
       grub_ehci_oper_write32 (e, GRUB_EHCI_COMMAND,
 			      GRUB_EHCI_CMD_RUNSTOP |