Hi,

The 8250 serial driver detects the Exar XR16L2551 as a 16550A.  The
XR16L2551 has an EFR register and sleep capabilities (UART_CAP_FIFO |
UART_CAP_EFR | UART_CAP_SLEEP).  However, broken_efr() thinks it's a
buggy Exar ST16C255x.

Any suggestion on how to differentiate between the two parts?  Exar have
made the ST16C255x with the same registers as the XR16L255x...

Perhaps it's okay for the ST16C255x to be detected as something with
UART_CAP_EFR | UART_CAP_SLEEP even if it doesn't work? i.e., by removing
broken_efr().

Also, the initial IER test was failing (after a soft reboot) with the
XR16L2551 part since the sleep mode bit was set but was read-only.  It
seems sensible to make this test only look at the lower 4 bits.

David Vrabel
-- 
David Vrabel, Design Engineer

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