serial: pxa: work around for errata #20
Errata E20: UART: Character Timeout interrupt remains set under certain software conditions. Implication: The software servicing the UART can be trapped in an infinite loop. Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -100,6 +100,16 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status)
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int max_count = 256;
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do {
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/* work around Errata #20 according to
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* Intel(R) PXA27x Processor Family
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* Specification Update (May 2005)
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*
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* Step 2
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* Disable the Reciever Time Out Interrupt via IER[RTOEI]
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*/
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up->ier &= ~UART_IER_RTOIE;
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serial_out(up, UART_IER, up->ier);
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ch = serial_in(up, UART_RX);
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flag = TTY_NORMAL;
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up->port.icount.rx++;
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@ -156,6 +166,16 @@ static inline void receive_chars(struct uart_pxa_port *up, int *status)
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*status = serial_in(up, UART_LSR);
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} while ((*status & UART_LSR_DR) && (max_count-- > 0));
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tty_flip_buffer_push(tty);
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/* work around Errata #20 according to
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* Intel(R) PXA27x Processor Family
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* Specification Update (May 2005)
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*
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* Step 6:
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* No more data in FIFO: Re-enable RTO interrupt via IER[RTOIE]
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*/
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up->ier |= UART_IER_RTOIE;
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serial_out(up, UART_IER, up->ier);
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}
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static void transmit_chars(struct uart_pxa_port *up)
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