PING: [PATCH v4 TRIVIAL 1/2] ARM: Enable GICv2m on 32-bit virt machine

Russell King - ARM Linux linux at
Wed Oct 7 09:26:02 PDT 2015

On Wed, Oct 07, 2015 at 01:43:30PM +0100, Marc Zyngier wrote:
> On 07/10/15 12:29, Russell King - ARM Linux wrote:
> > On Wed, Oct 07, 2015 at 02:02:23PM +0300, Pavel Fedin wrote:
> >>  2/2 from this series has been ACKed and picked up by Marc Zynger. He
> >> told me that 1/2 is your area of competence.
> > 
> > ... which is kind of funny, because all of ARM Ltd's platforms that
> > have PCIe on the board, and thus might have MSI, the PCIe is non-
> > functional.  So, until SolidRun sent me an Armada 388 platform a few
> > weeks back, I had zero MSI platforms, and zero MSI knowledge.
> > 
> > Just because code falls into a particular area of the tree does not
> > mean that the person who's looking after that area knows everything
> > inside out - especially when it comes to architecture maintanence
> > and the code in that subtree covers virtually every technology out
> > there, and the maintainer is kept functional hardware-starved [*].
> > 
> > Now, the Armada 388 doesn't use the GIC for MSI, but uses its own
> > interrupt controller.  I haven't yet worked out which bits of the
> > kernel are being used to provide this functionality yet, but I know
> > it works.  What I don't want to do is to merge your patch and then
> > have my one and only MSI platform break because of it, so what I'm
> > looking for is an assurance that this has had some exposure on
> > non-GIC MSI platforms, or has been reviewed with this in mind.
> > 
> > We're having far too many regressions of the kind of "let's get X
> > working on platform Y which then causes platform Z to break".
> > 
> > 
> > * - I'm not saying that I want more hardware; I've been out of physical
> > space for new hardware for some time, and the few extra platforms I've
> > received recently are having to be stacked on top of each other - which
> > isn't good when they're bare boards.  It would be nice, however, if the
> > hardware I did have was fully functional!
> > 
> The generic MSI domain (which is what asm-generic/msi.h is about -
> nothing GIC specific about it) is entirely isolated from the rest of the
> MSI infrastructure used on 32bit ARM, and is very unlikely to introduce
> any regression.

That's good to hear.  Okay, let's get this patch in the patch system then,
and I'll see whether it has any effect on Armada 388.

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