[PATCH REPOST 2/2] serial/amba-pl011: Leave the TX IRQ alone when the UART is not open

Dave Martin Dave.Martin at arm.com
Thu Mar 12 05:56:04 PDT 2015

On Thu, Mar 12, 2015 at 11:04:41AM +0000, Russell King - ARM Linux wrote:
> On Wed, Mar 04, 2015 at 12:27:34PM +0000, Dave Martin wrote:
> > Getting the TX IRQ re-asserted from scratch can be inefficient in
> > some setups.
> > 
> > This patch avoids clearing the TX IRQ across pl011_shutdown()...
> > pl011_startup(), so that if the port is closed and reopened, the
> > IRQ will still work afterwards without having to bootstrap it again.
> So if a port is being used as the console, we end up spraying the system
> with transmit interrupts?  This can't be right.

Nope, if the port is not open theough serial_core then TXIS remains
asserted but is masked off in IMSC.

This should be  just the same as the way we avoid a screaming TX interrupt
when the port *is* open but the transmitter is idle.

My commit message could have explained that better...


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