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serial: 8250: Check UART_SCR is writable
Au1x00/RT2800+ doesn't implement the 8250 scratch register (and
this may be true of other h/w currently supported by the 8250 driver);
read back the canary value written to the scratch register to enable
the console h/w restart after resume from system suspend.
Fixes: 4516d50aab ("serial: 8250: Use canary to restart console ...")
Reported-by: Mason <[email protected]>
Signed-off-by: Peter Hurley <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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1 changed files with 2 additions and 1 deletions
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@ -3585,7 +3585,8 @@ void serial8250_suspend_port(int line)
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port->type != PORT_8250) {
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unsigned char canary = 0xa5;
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serial_out(up, UART_SCR, canary);
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up->canary = canary;
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if (serial_in(up, UART_SCR) == canary)
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up->canary = canary;
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}
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uart_suspend_port(&serial8250_reg, port);
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