TI PCIe xHCI and kexec

From: Joel Stanley
Date: Tue Feb 04 2020 - 19:56:01 EST


I'm supporting a system that uses Linux-as-a-bootloader to load a
distro kernel via kexec, The systems have a TI TUSB73x0 PCIe
controller which goes out to lunch after a kexec. This is the distro
(post-kexec) kernel:

[ 0.235411] pci 0003:01:00.0: xHCI HW did not halt within 16000
usec status = 0x0
[ 1.037298] xhci_hcd 0003:01:00.0: xHCI Host Controller
[ 1.037367] xhci_hcd 0003:01:00.0: new USB bus registered, assigned
bus number 1
[ 1.053481] xhci_hcd 0003:01:00.0: Host halt failed, -110
[ 1.053523] xhci_hcd 0003:01:00.0: can't setup: -110
[ 1.053565] xhci_hcd 0003:01:00.0: USB bus 1 deregistered
[ 1.053629] xhci_hcd 0003:01:00.0: init 0003:01:00.0 fail, -110
[ 1.053703] xhci_hcd: probe of 0003:01:00.0 failed with error -110

There were some fixes made a few years back to improve the situation,
but we've still had to carry some form of the patch below in the
bootloader kernel. I would like to rework it so it can be merged.

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index dbac0fa9748d..eaa94456dd9d 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -789,6 +789,9 @@ void xhci_shutdown(struct usb_hcd *hcd)
xhci_dbg_trace(xhci, trace_xhci_dbg_init,
"xhci_shutdown completed - status = %x",
readl(&xhci->op_regs->status));
+
+ /* TI XHCI controllers do not come back after kexec without this hack */
+ pci_reset_function_locked(to_pci_dev(hcd->self.sysdev));
}
EXPORT_SYMBOL_GPL(xhci_shutdown);

I would like some advice on how to implement it in a way that is
acceptable. Would a quirk on the pci id in xhci_shutdown be ok?

0003:01:00.0 USB controller: Texas Instruments TUSB73x0 SuperSpeed USB
3.0 xHCI Host Controller (rev 02)

The full debug log of the distro kernel booting is below.

Cheers,

Joel

---

[ 1.037638] xhci_hcd 0003:01:00.0: xHCI Host Controller
[ 1.037695] xhci_hcd 0003:01:00.0: new USB bus registered, assigned
bus number 1
[ 1.037789] xhci_hcd 0003:01:00.0: xHCI capability registers at
(ptrval):
[ 1.037792] xhci_hcd 0003:01:00.0: CAPLENGTH AND HCIVERSION 0x960020:
[ 1.037794] xhci_hcd 0003:01:00.0: CAPLENGTH: 0x20
[ 1.037796] xhci_hcd 0003:01:00.0: HCIVERSION: 0x96
[ 1.037798] xhci_hcd 0003:01:00.0: HCSPARAMS 1: 0x8000840
[ 1.037800] xhci_hcd 0003:01:00.0: Max device slots: 64
[ 1.037802] xhci_hcd 0003:01:00.0: Max interrupters: 8
[ 1.037804] xhci_hcd 0003:01:00.0: Max ports: 8
[ 1.037806] xhci_hcd 0003:01:00.0: HCSPARAMS 2: 0xc0000f1
[ 1.037808] xhci_hcd 0003:01:00.0: Isoc scheduling threshold: 1
[ 1.037810] xhci_hcd 0003:01:00.0: Maximum allowed segments in
event ring: 15
[ 1.037813] xhci_hcd 0003:01:00.0: HCSPARAMS 3 0x7ff000a:
[ 1.037815] xhci_hcd 0003:01:00.0: Worst case U1 device exit latency: 10
[ 1.037816] xhci_hcd 0003:01:00.0: Worst case U2 device exit latency: 2047
[ 1.037819] xhci_hcd 0003:01:00.0: HCC PARAMS 0x270f06d:
[ 1.037821] xhci_hcd 0003:01:00.0: HC generates 64 bit addresses
[ 1.037823] xhci_hcd 0003:01:00.0: HC hasn't Contiguous Frame ID Capability
[ 1.037825] xhci_hcd 0003:01:00.0: HC can't generate Stopped -
Short Package event
[ 1.037826] xhci_hcd 0003:01:00.0: FIXME: more HCCPARAMS debugging
[ 1.037829] xhci_hcd 0003:01:00.0: RTSOFF 0x4a0:
[ 1.037831] xhci_hcd 0003:01:00.0: xHCI operational registers at
(ptrval):
[ 1.037833] xhci_hcd 0003:01:00.0: USBCMD 0x0:
[ 1.037835] xhci_hcd 0003:01:00.0: HC is being stopped
[ 1.037837] xhci_hcd 0003:01:00.0: HC has finished hard reset
[ 1.037839] xhci_hcd 0003:01:00.0: Event Interrupts disabled
[ 1.037841] xhci_hcd 0003:01:00.0: Host System Error Interrupts disabled
[ 1.037843] xhci_hcd 0003:01:00.0: HC has finished light reset
[ 1.037846] xhci_hcd 0003:01:00.0: USBSTS 0x0:
[ 1.037847] xhci_hcd 0003:01:00.0: Event ring is empty
[ 1.037849] xhci_hcd 0003:01:00.0: No Host System Error
[ 1.037851] xhci_hcd 0003:01:00.0: HC is running
[ 1.037854] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0x2a0
[ 1.037857] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037860] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037862] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037865] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0x2a0
[ 1.037868] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037870] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037873] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037876] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0xe03
[ 1.037878] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037881] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037884] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037886] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0xe03
[ 1.037889] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037892] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037894] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037897] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0x2a0
[ 1.037900] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037902] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037905] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037908] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0x2a0
[ 1.037910] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037913] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037916] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037918] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0x2a0
[ 1.037921] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037924] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037926] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037929] xhci_hcd 0003:01:00.0: (ptrval) port status reg = 0x2a0
[ 1.037931] xhci_hcd 0003:01:00.0: (ptrval) port power reg = 0x0
[ 1.037934] xhci_hcd 0003:01:00.0: (ptrval) port link reg = 0x0
[ 1.037937] xhci_hcd 0003:01:00.0: (ptrval) port reserved reg = 0x0
[ 1.037939] xhci_hcd 0003:01:00.0: // Halt the HC
[ 1.053945] xhci_hcd 0003:01:00.0: Host halt failed, -110
[ 1.053987] xhci_hcd 0003:01:00.0: can't setup: -110
[ 1.054032] xhci_hcd 0003:01:00.0: USB bus 1 deregistered
[ 1.054099] xhci_hcd 0003:01:00.0: init 0003:01:00.0 fail, -110
[ 1.054165] xhci_hcd: probe of 0003:01:00.0 failed with error -110