Re: [Xen-devel] [for-4.7 1/5] drivers/pl011: ACPI: The interrupt should always be high level triggered

[Julien Grall <julien.grall@xxxxxxx>]

On 07/04/16 14:57, Shannon Zhao wrote:
> On 2016年04月07日 21:41, Julien Grall wrote:
> > On 07/04/16 13:30, Shannon Zhao wrote:
> > > On 2016/4/7 18:59, Julien Grall wrote:
> > > > The SPCR does not specify if the interrupt is edge or level triggered.
> > > > So the configuration needs to be hardcoded in the code.
> > > >
> > > > Based on the PL011 TRM (see 2.2.8 in ARM DDI 0183G), the interrupt
> > > > generated
> > > > will be active high. This wording implies the interrupt should be
> > > > high level
> > > > triggered.
> > > I think active high can stand rising edge triggered for edge triggered
> > > interrupt.
> > >
> > > E.g. see "Table 5-118 Flag Definitions: Virtual Timer, EL2 timers, and
> > > Secure & Non-Secure EL1 timers" in ACPI SPEC 6.0.
> > I've spoken with multiple person about the wording and the consensus is
> > "active high" would imply high level triggered. So it's very ambiguous.
> >
> > However, the PL011 is always using a high level triggered. You can look
> > at the device tree bindings such as the one for the foundation model.
> >
> > Also, the SBSA (section 4.3.2 in ARM-DEN-0029 v2.3) states the PL011
> > implemented with a level triggered interrupt.
> >
> > Note, I wasn't able to get the serial console working on my platform
> > with edge triggered interrupt.
> So how about IRQ_TYPE_LEVEL_HIGH instead of IRQ_TYPE_LEVEL_MASK?
Good point. I will likely resend only this patch and update the commit 
message too.
Regards,

--
Julien Grall

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