usb: xhci: remove legacy 'num_trbs_free' tracking

Keeping track of free TRBs in a ring by adding and subtracting each time
a enqueue or dequeue pointer is modified has proven to be buggy and
complicated, especially over long periods of time.
The xhci driver has already moved to calculating free TRBs dynamically
based on ring size and the enqueue/dequeue positions.

The DbC path is the last user of 'num_trbs_free'. Rather than maintaining
two separate accounting mechanisms, remove the field entirely and switch
DbC to use xhci_num_trbs_free(). Since 'num_trbs_free' undercounts by one,
and xhci_num_trbs_free() does not, the check for sufficient free TRBs is
adjusted.

Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://patch.msgid.link/20260603091132.1110849-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

0 files changed, 0 insertions, 0 deletions