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xhci is unusable on some systems after driver switched to BIT() macro. Upper 32bits of 64bit CRCR command register are unintentionally cleared. Seen 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. 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. The CRCR register is 64 bits wide - commitabe93f27cd("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. [Mathias: use BIT_ULL() for ERST_EHB and EP_CTX_CYCLE_MASK as suggested by Michal Pecio, also include raspberry case in commit message] Fixes:abe93f27cd("xhci: use BIT macro") Cc: stable <stable@kernel.org> Assisted-by: Claude:claude-sonnet-5 cc: Michal Pecio <michal.pecio@gmail.com> Signed-off-by: Lachlan Hodges <lachlan.hodges@morsemicro.com> Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com> Link: https://patch.msgid.link/20260804083639.2148950-2-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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