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    SubjectRe: [PATCH 3/3] 8250: add workaround for MPC8[356]xx UART break IRQ storm

    > @@ -1553,7 +1554,15 @@ static void serial8250_handle_port(struct
    > uart_8250_port *up)
    > spin_lock_irqsave(&up->port.lock, flags);
    > - status = serial_inp(up, UART_LSR);
    > + /* Workaround for IRQ storm errata on break with Freescale
    > 16550 */
    > + if (UART_BUG_FSLBK & up->port.bugs && up->lsr_last &
    > UART_LSR_BI) {
    > + up->lsr_last &= ~UART_LSR_BI;
    > + serial_inp(up, UART_RX);
    > + spin_unlock_irqrestore(&up->port.lock, flags);
    > + return;
    > + }
    > +
    > + status = up->lsr_last = serial_inp(up, UART_LSR);

    We've now had a recent pile of IRQ function changes adding more quirk
    bits and special casing. This doesn't scale. We either need to make
    handle_port a method the specific drivers can override or you could
    hide the mess in your serial_inp implementation and not touch any core

    I really don't mind which but I suspect dealing with it in your
    serial_inp handler so that when you read UART_LSR you do the fixup
    might be simplest providing you can just do that.

    Sorting out a ->handle_port override is probably ultimately the right
    thing to do and then we can push some of the other funnies out further.

    At this point it's becoming increasingly clear that 8250 UART cloners
    are both very bad at cloning the things accurately, and very busy adding
    extra useful features so we need to start to treat 8250.c as a library
    you can wrap.


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      Last update: 2011-12-02 01:49    [W:0.020 / U:209.556 seconds]
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