[RFC PATCH] usb: xhci: use BIT_ULL for CRCR bits

The CRCR register is 64 bits wide - commit abe93f27cdd7
("xhci: use BIT macro") changed the flag definitions from (1 << n),
a signed int, to BIT(n), an unsigned long. Within
xhci_set_cmd_ring_deq(), the following operation is performed on the
CRCR register:

...
	crcr &= ~CMD_RING_PTR_MASK;
	crcr |= deq_dma;
	crcr &= ~CMD_RING_CYCLE;
	crcr |= xhci->cmd_ring->cycle_state;
...

Previously, ~CMD_RING_CYCLE was ~(int)1, a negative signed value
(0xFFFFFFFE with the sign bit set). Widening a negative signed int to
u64 sign-extends it to 0xFFFFFFFFFFFFFFFE, correctly clearing only bit
0 and preserving the 64-bit pointer written two lines above.

After the change when running on 32 bit kernels, ~CMD_RING_CYCLE is
~(unsigned long)1UL. On a 32-bit host this is an unsigned 32-bit
value (0xFFFFFFFE, no sign bit). Widening an unsigned value to u64
zero-extends it instead (0x00000000FFFFFFFE), so the subsequent AND
silently clears bits 63:32 of crcr, truncating the command ring
pointer that was just written before the value reaches hardware.

To fix, similar to how CMD_RING_PTR_MASK is defined, make sure we
use the BIT_ULL variant when defining the CRCR bits.

Fixes: abe93f27cdd7 ("xhci: use BIT macro")
Assisted-by: Claude:claude-sonnet-5
Signed-off-by: Lachlan Hodges <[email protected]>
---

Hi, I experienced this when running the tip of wireless-next on
a raspberry pi 4B compiled for arm32. The main symptoms were the
following log message:

[    0.549897] raspberrypi-firmware soc:firmware: Attached to firmware from 2021-02-25T12:11:39
[    0.626859] xhci_hcd 0000:01:00.0: xHCI Host Controller
[    0.626889] xhci_hcd 0000:01:00.0: new USB bus registered, assigned bus number 1
[    0.812619] xhci_hcd 0000:01:00.0: hcc params 0x002841eb hci version 0x100 quirks 0x0000200000000890
[    0.813188] xhci_hcd 0000:01:00.0: xHCI Host Controller
[    0.813203] xhci_hcd 0000:01:00.0: new USB bus registered, assigned bus number 2
[    0.813219] xhci_hcd 0000:01:00.0: Host supports USB 3.0 SuperSpeed
[    0.813602] hub 1-0:1.0: USB hub found
[    0.814052] hub 2-0:1.0: USB hub found
[    0.952714] xhci_hcd 0000:01:00.0: ERROR mismatched command completion event

Additionally running lsusb just hangs. Running the same kernel compiled
for aarch64 worked fine. Bisected to the commit in the Fixes line
above. Additionally a USB device plugged in to the USB3.0 (or 2.0)
did not enumerate. Once this patch is applied the USB device
enumerates properly on the tip of wireless-next 4a0bd262df75 ("wifi:
mac80211: fix per-STA profile length in cross-link CSA parsing").

Happy to test alternate fix proposals! Thanks.

lachlan
---
 drivers/usb/host/xhci.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index d02046a573e4..df014855c659 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -190,13 +190,13 @@ struct xhci_op_regs {
 
 /* CRCR - Command Ring Control Register - cmd_ring bitmasks */
 /* bit 0 - Cycle bit indicates the ownership of the command ring */
-#define CMD_RING_CYCLE		BIT(0)
+#define CMD_RING_CYCLE		BIT_ULL(0)
 /* stop ring operation after completion of the currently executing command */
-#define CMD_RING_PAUSE		BIT(1)
+#define CMD_RING_PAUSE		BIT_ULL(1)
 /* stop ring immediately - abort the currently executing command */
-#define CMD_RING_ABORT		BIT(2)
+#define CMD_RING_ABORT		BIT_ULL(2)
 /* true: command ring is running */
-#define CMD_RING_RUNNING	BIT(3)
+#define CMD_RING_RUNNING	BIT_ULL(3)
 /* bits 63:6 - Command Ring pointer */
 #define CMD_RING_PTR_MASK	GENMASK_ULL(63, 6)
 
-- 
2.43.0