PCODE_READY
if ((xe_mmio_read32(mmio, PCODE_MAILBOX) & PCODE_READY) != 0)
xe_mmio_write32(mmio, PCODE_MAILBOX, PCODE_READY | mbox);
err = xe_mmio_wait32(mmio, PCODE_MAILBOX, PCODE_READY, 0,