[1/2] hw: usb: xhci: Add property to support writing ERSTBA in high-low order

Commit Message

Guenter Roeck April 5, 2025, 2 p.m. UTC

According to the XHCI specification, ERSTBA should be written in Low-High
order. The Linux kernel writes the high word first. This results in an
initialization failure.

The following information is found in the Linux kernel commit log.

[Synopsys]- The host controller was design to support ERST setting
during the RUN state. But since there is a limitation in controller
in supporting separate ERSTBA_HI and ERSTBA_LO programming,
It is supported when the ERSTBA is programmed in 64bit,
or in 32 bit mode ERSTBA_HI before ERSTBA_LO

[Synopsys]- The internal initialization of event ring fetches
the "Event Ring Segment Table Entry" based on the indication of
ERSTBA_LO written.

Add property to support writing the high word first.

Signed-off-by: Guenter Roeck <[e-mail]>
---
 hw/usb/hcd-xhci.c | 8 +++++++-
 hw/usb/hcd-xhci.h | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

Patch

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 64c3a23b9b..8c0ba569c8 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -3107,10 +3107,15 @@  static void xhci_runtime_write(void *ptr, hwaddr reg,
         } else {
             intr->erstba_low = val & 0xffffffc0;
         }
+        if (xhci->erstba_hi_lo) {
+            xhci_er_reset(xhci, v);
+        }
         break;
     case 0x14: /* ERSTBA high */
         intr->erstba_high = val;
-        xhci_er_reset(xhci, v);
+        if (!xhci->erstba_hi_lo) {
+            xhci_er_reset(xhci, v);
+        }
         break;
     case 0x18: /* ERDP low */
         if (val & ERDP_EHB) {
@@ -3636,6 +3641,7 @@  static const Property xhci_properties[] = {
     DEFINE_PROP_UINT32("p3",    XHCIState, numports_3, 4),
     DEFINE_PROP_LINK("host",    XHCIState, hostOpaque, TYPE_DEVICE,
                      DeviceState *),
+    DEFINE_PROP_BOOL("erstba-hi-lo", XHCIState, erstba_hi_lo, false),
 };
 
 static void xhci_class_init(ObjectClass *klass, void *data)
diff --git a/hw/usb/hcd-xhci.h b/hw/usb/hcd-xhci.h
index 9c3974f148..cf3f074261 100644
--- a/hw/usb/hcd-xhci.h
+++ b/hw/usb/hcd-xhci.h
@@ -189,6 +189,7 @@  typedef struct XHCIState {
     uint32_t numports_3;
     uint32_t numintrs;
     uint32_t numslots;
+    bool erstba_hi_lo;
     uint32_t flags;
     uint32_t max_pstreams_mask;
     void (*intr_update)(XHCIState *s, int n, bool enable);