GICv3: Support for active low level-sensitive PPIs in device-tree binding

GICv3: Support for active low level-sensitive PPIs in device-tree binding

[bhupesh.sharma at freescale.com]

Hi,

While the GICv2 device-tree binding document (see [1]) seems to have support for active low level-sensitive PPIs:

The 3rd cell is the flags, encoded as follows:
	bits[3:0] trigger type and level flags.
		1 = low-to-high edge triggered
		2 = high-to-low edge triggered (invalid for SPIs)
		4 = active high level-sensitive
		8 = active low level-sensitive (invalid for SPIs).

The GICv3 device-tree bindings (see [2]) on the other hand, seem to be lacking the same for active low level-sensitive PPIs:

  The 3rd cell is the flags, encoded as follows:
	bits[3:0] trigger type and level flags.
		1 = edge triggered
		4 = level triggered

One of our SoC, supports active low level-sensitive PPIs on GICv3. If I spin-out a patch to address the same in GICv3 bindings,
will that be acceptable, or, is something on similar lines already in-work.

[1] https://git.kernel.org/cgit/linux/kernel/git/arm/arm-soc.git/tree/Documentation/devicetree/bindings/arm/gic.txt?h=for-next 

[2] https://git.kernel.org/cgit/linux/kernel/git/arm/arm-soc.git/tree/Documentation/devicetree/bindings/arm/gic-v3.txt?h=for-next

Regards,
Bhupesh

GICv3: Support for active low level-sensitive PPIs in device-tree binding

[Marc Zyngier]

On Fri, 27 Feb 2015 11:13:08 +0000
"bhupesh.sharma at freescale.com" <bhupesh.sharma@freescale.com> wrote:

> Hi,
> 
> While the GICv2 device-tree binding document (see [1]) seems to have
> support for active low level-sensitive PPIs:
> 
> The 3rd cell is the flags, encoded as follows:
> 	bits[3:0] trigger type and level flags.
> 		1 = low-to-high edge triggered
> 		2 = high-to-low edge triggered (invalid for SPIs)
> 		4 = active high level-sensitive
> 		8 = active low level-sensitive (invalid for SPIs).
> 
> The GICv3 device-tree bindings (see [2]) on the other hand, seem to
> be lacking the same for active low level-sensitive PPIs:
> 
>   The 3rd cell is the flags, encoded as follows:
> 	bits[3:0] trigger type and level flags.
> 		1 = edge triggered
> 		4 = level triggered
> 
> One of our SoC, supports active low level-sensitive PPIs on GICv3. If
> I spin-out a patch to address the same in GICv3 bindings, will that
> be acceptable, or, is something on similar lines already in-work.

Yes, please send in a patch (possible saying "valid for PPIs only"
instead of "invalid for SPIs", so that we don't have to restrict it
for LPIs either).

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny.

GICv3: Support for active low level-sensitive PPIs in device-tree binding

[bhupesh.sharma at freescale.com]

> -----Original Message-----
> From: Marc Zyngier [mailto:marc.zyngier at arm.com]
> Sent: Friday, February 27, 2015 4:56 PM
> To: Sharma Bhupesh-B45370
> Cc: Mark Rutland; Will Deacon; linux-arm-kernel at lists.infradead.org;
> arnd at arndb.de
> Subject: Re: GICv3: Support for active low level-sensitive PPIs in
> device-tree binding
> 
> On Fri, 27 Feb 2015 11:13:08 +0000
> "bhupesh.sharma at freescale.com" <bhupesh.sharma@freescale.com> wrote:
> 
> > Hi,
> >
> > While the GICv2 device-tree binding document (see [1]) seems to have
> > support for active low level-sensitive PPIs:
> >
> > The 3rd cell is the flags, encoded as follows:
> > 	bits[3:0] trigger type and level flags.
> > 		1 = low-to-high edge triggered
> > 		2 = high-to-low edge triggered (invalid for SPIs)
> > 		4 = active high level-sensitive
> > 		8 = active low level-sensitive (invalid for SPIs).
> >
> > The GICv3 device-tree bindings (see [2]) on the other hand, seem to be
> > lacking the same for active low level-sensitive PPIs:
> >
> >   The 3rd cell is the flags, encoded as follows:
> > 	bits[3:0] trigger type and level flags.
> > 		1 = edge triggered
> > 		4 = level triggered
> >
> > One of our SoC, supports active low level-sensitive PPIs on GICv3. If
> > I spin-out a patch to address the same in GICv3 bindings, will that be
> > acceptable, or, is something on similar lines already in-work.
> 
> Yes, please send in a patch (possible saying "valid for PPIs only"
> instead of "invalid for SPIs", so that we don't have to restrict it for
> LPIs either).
> 

Sure Marc. Thanks, I will soon send a patch.

Regards,
Bhupesh