Re: [PATCH 2/2] powerpc: add support for MPIC message register API

[Scott Wood <scottwood@freescale.com>]

On Fri, 29 Apr 2011 17:27:06 +0000
Kushwaha Prabhakar-B32579 <B32579@freescale.com> wrote:

> 
> 
> > > Hi,
> > >
> > > I have no comments about coding and architecture. It looks fine.
> > >
> > > Only have a query about its use case..
> > >    "Any application intended to use message interrupt requires to know
> > reg_num because of struct mpic_msgr* mpic_msgr_get(unsigned int reg_num)
> > API"
> > >
> > > It will be good to search available unit internally and provide its
> > pointer. It will make application more flexible.
> > >
> > 
> > The problem is that you fundamentally cannot implement an allocator for
> > MSG registers if you're going to communicate with another kernel (how
> > would both kernels' allocators be synchronized?). So the message register
> > allocation must be decided at design time, not run time.
> > 
> 
> I agree with you..  It is true while communicating with another kernel.
> But message interrupts can be used by different independent drivers within same kernel. For eg. PCIe and Ethernet driver. 
> As per current design both drivers needs to be in sync before requesting any message unit for avoiding any conflict. As these drivers are completely independent. It is very difficult. 
> 
> Can it be possible to provide new API to take care it.

Do you have a real use case in mind where these message registers (not
MSIs) are used internally in this manner?

Perhaps an allocator could be added in the same patchset that adds such a
user.

-Scott