Comment #135 for bugzilla 237666 : a USB3-handling problem with a investigatory fix for a cortex-a72 context

[Mark Millard]

On 2020-Sep-19, at 12:45, Hans Petter Selasky <hps at selasky.org> wrote:

> On 2020-09-19 21:36, Mark Millard wrote:
>> # svnlite diff /usr/src/sys/dev/usb/controller/xhci.c
>> Index: /usr/src/sys/dev/usb/controller/xhci.c
>> ===================================================================
>> --- /usr/src/sys/dev/usb/controller/xhci.c	(revision 363590)
>> +++ /usr/src/sys/dev/usb/controller/xhci.c	(working copy)
>> @@ -441,6 +441,9 @@
>>    	DPRINTF("ERSTBA(0)=0x%016llx\n", (unsigned long long)addr);
>>  +#ifdef __aarch64__
>> +__asm __volatile("dsb st" : : : "memory");
>> +#endif
>>  	XWRITE4(sc, runt, XHCI_ERSTBA_LO(0), (uint32_t)addr);
>>  	XWRITE4(sc, runt, XHCI_ERSTBA_HI(0), (uint32_t)(addr >> 32));
>>  booted just fine. This is what I expected relative to
>> initializing for the event ring.
> 
> Can you replace this with a USB flush call?

Sure . . .

>> Index: xhci.c
>> ===================================================================
>> --- xhci.c	(revision 365238)
>> +++ xhci.c	(working copy)
>> @@ -432,6 +432,8 @@
>> 	phwr->hwr_ring_seg[0].qwEvrsTablePtr = htole64(addr);
>> 	phwr->hwr_ring_seg[0].dwEvrsTableSize = htole32(XHCI_MAX_EVENTS);
>> +	usb_bus_mem_flush_all(&sc->sc_bus, &xhci_iterate_hw_softc);
>> +
>> 	DPRINTF("ERDP(0)=0x%016llx\n", (unsigned long long)addr);
>>  	XWRITE4(sc, runt, XHCI_ERDP_LO(0), (uint32_t)addr);

In my context:

# svnlite diff /usr/src/sys/dev/usb/controller/xhci.c
Index: /usr/src/sys/dev/usb/controller/xhci.c
===================================================================
--- /usr/src/sys/dev/usb/controller/xhci.c	(revision 363590)
+++ /usr/src/sys/dev/usb/controller/xhci.c	(working copy)
@@ -431,6 +431,7 @@
 
 	phwr->hwr_ring_seg[0].qwEvrsTablePtr = htole64(addr);
 	phwr->hwr_ring_seg[0].dwEvrsTableSize = htole32(XHCI_MAX_EVENTS);
+	usb_bus_mem_flush_all(&sc->sc_bus, &xhci_iterate_hw_softc);
 
 	DPRINTF("ERDP(0)=0x%016llx\n", (unsigned long long)addr);
 

The result booted just fine, no "Resetting controller" notices at
all.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)