USB: early: Handle AMD's spec-compliant identifiers, too (7dbdb53d) · Commits · 戴 / test

This fixes a bug that causes the USB3 early console to freeze after printing a single line on AMD machines because it can't parse the Transfer TRB properly. The spec at https://www.intel.com/content/dam/www/public/us/en/documents/technical-specifications/extensible-host-controler-interface-usb-xhci.pdf says in section "4.5.1 Device Context Index" that the Context Index, also known as Endpoint ID according to section "1.6 Terms and Abbreviations", is normally computed as `DCI = (Endpoint Number * 2) + Direction`, which matches the current definitions of XDBC_EPID_OUT and XDBC_EPID_IN. However, the numbering in a Debug Capability Context data structure is supposed to be different: Section "7.6.3.2 Endpoint Contexts and Transfer Rings" explains that a Debug Capability Context data structure has the endpoints mapped to indices 0 and 1. Change XDBC_EPID_OUT/XDBC_EPID_IN to the spec-compliant values, add XDBC_EPID_OUT_INTEL/XDBC_EPID_IN_INTEL with Intel's incorrect values, and let xdbc_handle_tx_event() handle both. I have verified that with this patch applied, the USB3 early console works on both an Intel and an AMD machine. Fixes: ("usb/early: Add driver for xhci debug capability") Cc: stable@vger.kernel.org Signed-off-by:

Jann Horn <jannh@google.com> Link: https://lore.kernel.org/r/20200401074619.8024-1-jannh@google.com Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/early/xhci-dbc.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -728,19 +728,19 @@ static void xdbc_handle_tx_event(struct xdbc_trb *evt_trb)
		case COMP_USB_TRANSACTION_ERROR:
		case COMP_STALL_ERROR:
		default:
		if (ep_id == XDBC_EPID_OUT)
		if (ep_id == XDBC_EPID_OUT \|\| ep_id == XDBC_EPID_OUT_INTEL)
		xdbc.flags \|= XDBC_FLAGS_OUT_STALL;
		if (ep_id == XDBC_EPID_IN)
		if (ep_id == XDBC_EPID_IN \|\| ep_id == XDBC_EPID_IN_INTEL)
		xdbc.flags \|= XDBC_FLAGS_IN_STALL;

		xdbc_trace("endpoint %d stalled\n", ep_id);
		break;
		}

		if (ep_id == XDBC_EPID_IN) {
		if (ep_id == XDBC_EPID_IN \|\| ep_id == XDBC_EPID_IN_INTEL) {
		xdbc.flags &= ~XDBC_FLAGS_IN_PROCESS;
		xdbc_bulk_transfer(NULL, XDBC_MAX_PACKET, true);
		} else if (ep_id == XDBC_EPID_OUT) {
		} else if (ep_id == XDBC_EPID_OUT \|\| ep_id == XDBC_EPID_OUT_INTEL) {
		xdbc.flags &= ~XDBC_FLAGS_OUT_PROCESS;
		} else {
		xdbc_trace("invalid endpoint id %d\n", ep_id);

drivers/usb/early/xhci-dbc.h

+16 −2

Original line number	Diff line number	Diff line
		@@ -120,8 +120,22 @@ struct xdbc_ring {
		u32 cycle_state;
		};

		#define XDBC_EPID_OUT 2
		#define XDBC_EPID_IN 3
		/*
		* These are the "Endpoint ID" (also known as "Context Index") values for the
		* OUT Transfer Ring and the IN Transfer Ring of a Debug Capability Context data
		* structure.
		* According to the "eXtensible Host Controller Interface for Universal Serial
		* Bus (xHCI)" specification, section "7.6.3.2 Endpoint Contexts and Transfer
		* Rings", these should be 0 and 1, and those are the values AMD machines give
		* you; but Intel machines seem to use the formula from section "4.5.1 Device
		* Context Index", which is supposed to be used for the Device Context only.
		* Luckily the values from Intel don't overlap with those from AMD, so we can
		* just test for both.
		*/
		#define XDBC_EPID_OUT 0
		#define XDBC_EPID_IN 1
		#define XDBC_EPID_OUT_INTEL 2
		#define XDBC_EPID_IN_INTEL 3

		struct xdbc_state {
		u16 vendor;

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