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Re: [Xen-devel] [PATCH] add polling support for ns16550

To: Alex Williamson <alex.williamson@xxxxxx>
Subject: Re: [Xen-devel] [PATCH] add polling support for ns16550
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 24 Nov 2005 11:13:40 +0000
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On 23 Nov 2005, at 16:40, Alex Williamson wrote:

  The patch below adds ac_timer based polling to the ns16550 UART
driver.  This is useful when the interrupt line is not connected in
hardware or the mechanism to enable it is not readily available in the
hypervisor.  Polling is only enabled when the UART IRQ is set to zero.
Thanks,

I reworked the patch a little and checked it in, thanks.

One thing I removed was the clear-and-reset of IER in the timeout handler. Given we write zero to IER in the preirq steup function, and also we do not set the master-enable bit in the MCR, I cannot see how you could end up accidentally fielding interrupts in the timeout handler. Did I miss something?

 -- Keir


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