RE: [PATCH 2/4] powerpc/mpic: Use the MPIC_LARGE_VECTORS flag for FSL MPIC.

-----Original Message-----
From: Kumar Gala [mailto:galak@kernel.crashing.org]
Sent: Tuesday, March 27, 2012 7:01 PM
To: Sethi Varun-B16395
Cc: Linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/4] powerpc/mpic: Use the MPIC_LARGE_VECTORS flag
for FSL MPIC.
=20
=20
On Mar 27, 2012, at 7:15 AM, Varun Sethi wrote:
=20

quoted

FSL MPIC supports 16 bit vectors so our vector number space isn't
restricted to 256 vectors. We should use the MPIC_LARG_VECTORS flag
while intializing the MPIC. This also prevents us from eating in to
hardware vector number space (MSIs) while setting up internal sources.

=20
What is driving this change?  The commit message isn't quite correct as
MPIC_LARGE_VECTORS is about the # of IRQs, not the fact that vector field
is 16-bits.
=20

[Sethi Varun-B16395] We derive the internal interrupt source vector numbers=
 from the
number of supported hardware interrupt sources. With the current value of 2=
56
we end up using vector numbers (for internal sources) corresponding to actu=
al hardware
interrupts. With the MPIC_LARGE_VECTORS flag we can avoid eating in to hard=
ware vector
number space.

-Varun