From: robin.murphy@arm•com (Robin Murphy)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function
Date: Wed, 30 Sep 2015 16:39:30 +0100 [thread overview]
Message-ID: <560C0232.2010100@arm.com> (raw)
In-Reply-To: <1442944336-11754-2-git-send-email-marc.zyngier@arm.com>
Hi Marc,
On 22/09/15 18:52, Marc Zyngier wrote:
> of_parse_phandle_with_args() is slightly inflexible as it doesn't
> allow the (unusual) case where the #*-cells property is not defined.
> In order to support this, introduce of_parse_phandle_with_opt_args()
> which assumes that #*-cells is zero when it is not defined,
> as required by the msi-parent binding
>
> This is done by turning __of_parse_phandle_with_args into an even
> bigger monster, which is a bit frightening.
A monster indeed; I can't quite figure out the exact effect this change
has on of_count_phandle_with_args(), but I have a lingering doubt it may
be something undesirable, since AFAICS that's now going to proceed from
where it would have errored out before, with a count of -2.
I think it might be nicer to implement this by passing an extra "assume
zero if #cells not found" boolean to __of_parse_phandle_with_args().
Alternatively, what's the actual likelihood of legacy bindings being
mixed in with new ones? Could we not simply mandate that anyone adding
an MSI controller with #msi-cells to a DT must ensure any existing nodes
are also updated with #msi-cells = 0, and keep the legacy workaround
self-contained in the MSI layer? e.g. paraphrasing from patch 2/2:
msi_np = of_parse_phandle(np, "msi-parent", 0);
if (!of_property_read_bool(msi_np, "#msi-cells"))
return parse_this_thing(...);
else
while (!of_parse_phandle_with_opt_args(np, "msi-parent"...
if (parse_this_thing(...))
return;
Robin.
next prev parent reply other threads:[~2015-09-30 15:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-22 17:52 [PATCH 0/4] of: Handle multi-parent version of msi-parent Marc Zyngier
2015-09-22 17:52 ` [PATCH 1/4] of: Add of_parse_phandle_with_opt_args() helper function Marc Zyngier
2015-09-29 17:28 ` Rob Herring
2015-09-30 9:08 ` Marc Zyngier
2015-09-30 13:57 ` Mark Rutland
2015-09-30 15:39 ` Robin Murphy [this message]
2015-09-30 17:18 ` Marc Zyngier
2015-09-22 17:52 ` [PATCH 2/4] of: irq: Add support for the new definition of "msi-parent" Marc Zyngier
2015-09-23 14:39 ` Sergei Shtylyov
2015-09-27 10:29 ` Thomas Gleixner
2015-09-27 13:02 ` Sergei Shtylyov
2015-09-22 17:52 ` [PATCH 3/4] PCI/MSI: " Marc Zyngier
2015-09-22 17:52 ` [PATCH 4/4] irqchip/gic-v3-its: Parse new version of msi-parent property Marc Zyngier
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