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Thu, 07 Jan 2021 11:33:28 -0800 (PST) MIME-Version: 1.0 References: <20201218210750.3455872-1-saravanak@google.com> <2a6dbcc83d5aca7a3340e0cf4d751cdc@kernel.org> <20201231211240.GA2333246@robh.at.kernel.org> <877dovlgdl.wl-maz@kernel.org> In-Reply-To: From: Rob Herring Date: Thu, 7 Jan 2021 12:33:16 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] of: property: Add device link support for interrupts To: Saravana Kannan Cc: Marc Zyngier , Greg Kroah-Hartman , Frank Rowand , Kevin Hilman , Android Kernel Team , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 7, 2021 at 12:09 PM Saravana Kannan wrote: > > On Thu, Jan 7, 2021 at 10:39 AM Rob Herring wrote: > > > > On Wed, Jan 6, 2021 at 11:53 AM Saravana Kannan wrote: > > > > > > On Sat, Jan 2, 2021 at 3:37 AM Marc Zyngier wrote: > > > > > > > > On Thu, 31 Dec 2020 21:12:40 +0000, > > > > Rob Herring wrote: > > > > > > > > > > On Mon, Dec 21, 2020 at 09:30:45AM +0000, Marc Zyngier wrote: > > > > > > On 2020-12-18 21:07, Saravana Kannan wrote: > > > > > > > Add support for creating device links out of interrupts property. > > > > > > > > > > > > > > Cc: Marc Zyngier > > > > > > > Cc: Kevin Hilman > > > > > > > Signed-off-by: Saravana Kannan > > > > > > > --- > > > > > > > Rob/Greg, > > > > > > > > > > > > > > This might need to go into driver-core to avoid conflict > > > > > > > due to fw_devlink refactor series that merged there. > > > > > > > > > > > > > > Thanks, > > > > > > > Saravana > > > > > > > > > > > > > > > > > > > > > drivers/of/property.c | 17 +++++++++++++++++ > > > > > > > 1 file changed, 17 insertions(+) > > > > > > > > > > > > > > diff --git a/drivers/of/property.c b/drivers/of/property.c > > > > > > > index 5f9eed79a8aa..e56a5eae0a0b 100644 > > > > > > > --- a/drivers/of/property.c > > > > > > > +++ b/drivers/of/property.c > > > > > > > @@ -1271,6 +1271,22 @@ static struct device_node > > > > > > > *parse_iommu_maps(struct device_node *np, > > > > > > > return of_parse_phandle(np, prop_name, (index * 4) + 1); > > > > > > > } > > > > > > > > > > > > > > +static struct device_node *parse_interrupts(struct device_node *np, > > > > > > > + const char *prop_name, int index) > > > > > > > +{ > > > > > > > + struct device_node *sup; > > > > > > > + > > > > > > > + if (strcmp(prop_name, "interrupts") || index) > > > > > > > + return NULL; > > > > > > > + > > > > > > > + of_node_get(np); > > > > > > > + while (np && !(sup = of_parse_phandle(np, "interrupt-parent", 0))) > > > > > > > + np = of_get_next_parent(np); > > > > > > > + of_node_put(np); > > > > > > > + > > > > > > > + return sup; > > > > > > > +} > > > > > > > + > > > > > > > static const struct supplier_bindings of_supplier_bindings[] = { > > > > > > > { .parse_prop = parse_clocks, }, > > > > > > > { .parse_prop = parse_interconnects, }, > > > > > > > @@ -1296,6 +1312,7 @@ static const struct supplier_bindings > > > > > > > of_supplier_bindings[] = { > > > > > > > { .parse_prop = parse_pinctrl6, }, > > > > > > > { .parse_prop = parse_pinctrl7, }, > > > > > > > { .parse_prop = parse_pinctrl8, }, > > > > > > > + { .parse_prop = parse_interrupts, }, > > > > > > > { .parse_prop = parse_regulators, }, > > > > > > > { .parse_prop = parse_gpio, }, > > > > > > > { .parse_prop = parse_gpios, }, > > > > > > > > > > > > You don't really describe what this is for so I'm only guessing > > > > > > from the context. If you want to follow the interrupt hierarchy, > > > > > > "interrupt-parent" isn't enough. You also need to track > > > > > > things like interrupt-map, or anything that carries a phandle > > > > > > to an interrupt controller. > > > > > > > > > > We don't need to follow the hierarchy, we just need the immediate > > > > > dependencies. > > > > > > > > Indeed. I also wonder why this isn't just a irq_find_parent() call, TBH. > > > > > > Thanks Rob for explaining it. > > > > > > Marc, I wasn't sure if Rob would be okay with including of_irq.h here. > > > Also, I'm trying to keep of/property.c independent of the framework > > > code for now. The long term goal is to see if I can move out most of > > > this into the frameworks. But I want to do that after I sort of some > > > of the larger problems (like getting fw_devlink=on to work on all > > > devices first). Let me know if you have a strong preference for right > > > now, if not, I'd rather keep property.c independent for now. > > > > > > I wasn't aware of interrupt-map until a few weeks ago and didn't know > > > it carried phandles. I can add support for that too. There's no reason > > > for all of them to go in one patch though. > > > > > > > > > > > > But you are right that 'interrupt-map' also needs to be tracked. > > > > > > > > And 'interrupts-extended', while we're at it. > > > > > > This is already handled. > > > > > > > > > > > > > I also noticed that we define 'interrupt-parent' as a dependency to > > > > > parse, but that's wrong. The dependency is where 'interrupts' appears > > > > > and where 'interrupt-parent' appears is irrelevant. > > > > > > No, the interrupt-parent parsing is correct and it's needed for > > > interrupt controllers to probe in the right order. But > > > interrupt-parent is also needs to be looked at for parsing > > > "interrupts". > > > > If you parse 'interrupts' for interrupt controllers (which in turn > > will use 'interrupt-parent'), then you aren't going to need to track > > 'interrupt-parent' by itself. > > Do all interrupt controllers (that are not the root interrupt > controller) need to have "interrupts" property? If yes, then yeah, > that makes sense. But I vaguely remember that this wasn't the case for > some DT I saw. There are some cases of stacked controllers where it's implicit. > > Ah, here's one I found. > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/mt2701.dtsi#n209 Right, so this is one of several cases of custom interrupt mapping properties (mediatek,ext-irq-range). Really, 'interrupts' or 'interrupt-map' should have been used here, but 'interrupt-map' doesn't really scale well if you have large ranges of interrupts. To handle the dependency with just 'interrupt-parent', you need to find nodes that are themselves an 'interrupt-parent' and then find their 'interrupt-parent'. Rob