On Wed, Apr 01, 2020 at 09:46:19AM +0200, Jann Horn wrote: > 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: aeb9dd1de98c ("usb/early: Add driver for xhci debug capability") > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Jann Horn <jannh@xxxxxxxxxx> > --- > drivers/usb/early/xhci-dbc.c | 8 ++++---- > drivers/usb/early/xhci-dbc.h | 18 ++++++++++++++++-- > 2 files changed, 20 insertions(+), 6 deletions(-) > > diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c > index cac991173ac0..5a462a1d1896 100644 > --- a/drivers/usb/early/xhci-dbc.c > +++ b/drivers/usb/early/xhci-dbc.c > @@ -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); > diff --git a/drivers/usb/early/xhci-dbc.h b/drivers/usb/early/xhci-dbc.h > index 673686eeddd7..6e2b7266a695 100644 > --- a/drivers/usb/early/xhci-dbc.h > +++ b/drivers/usb/early/xhci-dbc.h > @@ -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; > -- > 2.26.0.rc2.310.g2932bb562d-goog > Thanks for this, I'll queue it up after 5.7-rc1 is out. greg k-h
