COMMANDS_PER_QUEUE
n = head_idx + COMMANDS_PER_QUEUE - cmd_q->qidx - 1;
return n % COMMANDS_PER_QUEUE; /* Always one unused spot */
cmd_q->qidx = (cmd_q->qidx + 1) % COMMANDS_PER_QUEUE;
BUILD_BUG_ON(COMMANDS_PER_QUEUE > 128);
#define QUEUE_SIZE_VAL ((ffs(COMMANDS_PER_QUEUE) - 2) & \
#define Q_SIZE(n) (COMMANDS_PER_QUEUE*(n))