[PATCHv3 3/3] ARM: mvebu: implement L2/PCIe deadlock workaround

[Jason Cooper]

On Thu, May 15, 2014 at 03:50:08PM +0200, Thomas Petazzoni wrote:
> Dear Jason Cooper,
> 
> On Thu, 15 May 2014 09:21:18 -0400, Jason Cooper wrote:
> 
> > > +
> > > +	if (of_machine_is_compatible("marvell,armada375") ||
> > > +	    of_machine_is_compatible("marvell,armada38x")) {
> > > +		arch_ioremap_caller = armada_pcie_wa_ioremap_caller;
> > > +		pci_ioremap_set_mem_type(MT_UNCACHED);
> > 
> > iiuc, this patch depends on 1/3.  So how would you like to handle it?
> 
> Seems like my long cover letters are not always read in their
> entirety :-)

It was, the 'u' comes from 'u'nderstanding the coverletter _and_ the
code. ;-)

One a side note, I should mention I find your detailed coverletters
extremely helpful for getting up to speed quickly on what the intention
of a series is.  Even better, the Link tag that's added to the commit
message allows future devs to be three clicks away from that
information.  Thanks for setting that standard.

Which makes me think, in a lot of cases, it's better to start at the top
of the thread when researching a patch.  The Message-Id of the
coverletter is always the first address in the References header.
Perhaps I should link to that instead, or add both.

> From my cover letter:
> 
>  * PATCH 3/3 uses both of the added infrastructures, as well as the
>    existing infrastructure to customize the behavior of ioremap() on a
>    per-platform basis, to implement the workaround for the Armada 375
>    and 38x SOCs. This patch should go through the mvebu maintainers
>    tree. However, it has a build dependency on PATCH 1/3 that needs to
>    be taken into account.
> 
> The last two sentences are the most important ones here :-)
> 
> Joke aside, I'm really open to your suggestions as to what the
> appropriate merging patch is. I know Russell prefers to have the ARM
> core code flow through his tree, which obviously make sense.
> 
> However, routing PATCH 3/3 through Russell tree is going to be a mess
> of conflicts when things will get merged by Linus, due to the numerous
> other changes we've been doing in mach-mvebu/board-v7.c.

Yep.

> So the only course of action I see right now is to work with Russell to
> have him pull patches 1 and 2, and then provide a stable branch/tag
> that you can merge as a dependency in whatever branch you decide to
> merge patch 3/3. Would that work?

Dunno.  I have a 100% failure rate getting Russell to create a stable
topic branch to resolve dependencies like these.  Unfortunately, I think
the answer is going to be resubmit 3/3 once 3.16-rc1 lands with 1/3 and
2/3.

Not the answer I want to give, but unfortunately, it's the most
realistic.

thx,

Jason.