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Device status can change without warning at any point in time. This effectively means that no amount of status checking before a command is submitted can guarantee that the device is not in an error condition when the command is later submitted. The clearest signal that a device is not able to process commands is if it fails to process commands. With the above understanding in hand, update cxl_pci_setup_mailbox() to validate the readiness of the mailbox once at the beginning of time, and then use timeouts and busy sequencing errors as the only occasions to report status. Just as before, unless and until the driver gains a reset recovery path, doorbell clearing failures by the device are fatal to mailbox operations. Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/164298413480.3018233.9643395389297971819.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>