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Re: [Xen-devel] [PATCH] PL011: fix reverse logic for interrupt mask register

On Wed, 2013-08-21 at 17:11 +0100, Julien Grall wrote:
> On 08/13/2013 04:12 PM, Andre Przywara wrote:
> > The PL011 IMSC register description is somehow fuzzy in the
> > documentation; by comparing it with the Linux implementation one can
> > see that the logic is actually reversed to Xen's implementation:
> > A "0" in field means interrupt disabled, a "1" enables it.
> > Therefore we enabled all interrupts instead of disabling them in the
> > beginning and later on masked the wrong interrupts.
> > Unclear how this worked on the Versatile Express, but this fix is
> > needed to get Calxeda Midway running (and works on VExpress, too).
> On my Versatile Express, the keyboard is unusable with this patch.
> Xen receives random keys and sometimes nothing is printed on the serial
> port.
> By reverting this patch on my tree, I'm able to use correctly the serial
> port.

:-/ Andre did say this patch worked on vexpress for him.

I'm pretty certain Andre's patch is correct in its own right. But the
fact that it worked before does seem to imply that there are other
issues with the pl011 driver, it's likely that this change has just
exposed a latent one.

Could this be related somehow to the baud rate setting change? I
wouldn't have expected so but "random keys" and nothingness could be a
symptom of incorrect baud too.

Does anyone have time to look into this?

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