[PATCH v1 1/2] hw/usb/hcd-ehci: Rename migration compatibility fetch address fields

[Jamin Lin <jamin_lin@aspeedtech.com>]

Rename the 32-bit fetch address migration helper fields to make
their purpose clearer.

These fields are only used for migration compatibility with older
machine types that transfer 32-bit fetch addresses in the migration
stream. They are not runtime fetch address state.

Also add comments to clarify the relationship between the migration
compatibility fields and the runtime 64-bit fetch address fields.

No functional change.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 hw/usb/hcd-ehci.h | 17 ++++++++++++++---
 hw/usb/hcd-ehci.c | 12 ++++++------
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/hw/usb/hcd-ehci.h b/hw/usb/hcd-ehci.h
index 3d57e1de5f..b5ac9c8670 100644
--- a/hw/usb/hcd-ehci.h
+++ b/hw/usb/hcd-ehci.h
@@ -262,6 +262,10 @@ struct EHCIState {
 
     /* properties */
     uint32_t maxframes;
+    /*
+     * Controls migration stream compatibility for old machine types.
+     * Old machine types only transfer 32-bit fetch addresses.
+     */
     bool migrate_fetch_addr_64bit;
     bool caps_64bit_addr;
     uint32_t ctrldssegment_default;
@@ -302,9 +306,16 @@ struct EHCIState {
     EHCIQueueHead aqueues;
     EHCIQueueHead pqueues;
 
-    /* which address to look at next */
-    uint32_t a_fetch_addr_32;
-    uint32_t p_fetch_addr_32;
+    /*
+     * which address to look at next
+     *
+     * Migration compatibility fields for old machine types that only
+     * support 32-bit fetch addresses in the migration stream.
+     *
+     * New machine types migrate the full 64-bit runtime fetch address.
+     */
+    uint32_t migrate_a_fetch_addr;
+    uint32_t migrate_p_fetch_addr;
     uint64_t a_fetch_addr;
     uint64_t p_fetch_addr;
 
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 62c3770ac5..56ac8f6ae5 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -2482,8 +2482,8 @@ static int usb_ehci_pre_save(void *opaque)
     ehci->frindex = new_frindex;
 
     if (!ehci->migrate_fetch_addr_64bit) {
-        ehci->a_fetch_addr_32 = ehci->a_fetch_addr;
-        ehci->p_fetch_addr_32 = ehci->p_fetch_addr;
+        ehci->migrate_a_fetch_addr = ehci->a_fetch_addr;
+        ehci->migrate_p_fetch_addr = ehci->p_fetch_addr;
     }
 
     return 0;
@@ -2507,8 +2507,8 @@ static int usb_ehci_post_load(void *opaque, int version_id)
     }
 
     if (!s->migrate_fetch_addr_64bit) {
-        s->a_fetch_addr = s->a_fetch_addr_32;
-        s->p_fetch_addr = s->p_fetch_addr_32;
+        s->a_fetch_addr = s->migrate_a_fetch_addr;
+        s->p_fetch_addr = s->migrate_p_fetch_addr;
     }
 
     return 0;
@@ -2571,9 +2571,9 @@ const VMStateDescription vmstate_ehci = {
         /* schedule state */
         VMSTATE_UINT32(astate, EHCIState),
         VMSTATE_UINT32(pstate, EHCIState),
-        VMSTATE_UINT32_TEST(a_fetch_addr_32, EHCIState,
+        VMSTATE_UINT32_TEST(migrate_a_fetch_addr, EHCIState,
                             ehci_fetch_addr_32_needed),
-        VMSTATE_UINT32_TEST(p_fetch_addr_32, EHCIState,
+        VMSTATE_UINT32_TEST(migrate_p_fetch_addr, EHCIState,
                             ehci_fetch_addr_32_needed),
         VMSTATE_UINT64_TEST(a_fetch_addr, EHCIState,
                             ehci_fetch_addr_64_needed),
-- 
2.43.0