Messages in this thread | | | Date | Thu, 09 Dec 2021 08:07:09 +0000 | From | Marc Zyngier <> | Subject | Re: [RFC PATCH] of: platform: Skip mapping of interrupts in of_device_alloc() |
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On 2021-12-09 00:10, Lad Prabhakar wrote: > of_device_alloc() in early boot stage creates a interrupt mapping if > there exists a "interrupts" property in the node. > > For hierarchical interrupt domains using "interrupts" property in the > node > bypassed the hierarchical setup and messed up the irq setup. > > This patch adds a check in of_device_alloc() to skip interrupt mapping > if > "not-interrupt-producer" property is present in the node. This allows > nodes to describe the interrupts using "interrupts" property. > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> > --- > Hi All, > > Spawning from discussion [1], here is simple patch (not the ideal > probably > welcome for suggestions) from stopping the OF code from creating a map > for > the interrupts when using "interrupts" property. > > [1] https://lore.kernel.org/lkml/87pmqrck2m.wl-maz@kernel.org/ > T/#mbd1e47c1981082aded4b32a52e2c04291e515508 > > Cheers, > Prabhakar > --- > drivers/of/platform.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/drivers/of/platform.c b/drivers/of/platform.c > index b3faf89744aa..629776ca1721 100644 > --- a/drivers/of/platform.c > +++ b/drivers/of/platform.c > @@ -114,7 +114,7 @@ struct platform_device *of_device_alloc(struct > device_node *np, > struct device *parent) > { > struct platform_device *dev; > - int rc, i, num_reg = 0, num_irq; > + int rc, i, num_reg = 0, num_irq = 0; > struct resource *res, temp_res; > > dev = platform_device_alloc("", PLATFORM_DEVID_NONE); > @@ -124,7 +124,14 @@ struct platform_device *of_device_alloc(struct > device_node *np, > /* count the io and irq resources */ > while (of_address_to_resource(np, num_reg, &temp_res) == 0) > num_reg++; > - num_irq = of_irq_count(np); > + > + /* > + * we don't want to map the interrupts of hierarchical interrupt > domain > + * into the parent domain yet. This will be the job of the > hierarchical > + * interrupt driver code to map the interrupts as and when needed. > + */ > + if (!of_property_read_bool(np, "not-interrupt-producer"))
I don't think this is right. If anything, the expected behaviour should be indicated by the driver and not the device node.
> + num_irq = of_irq_count(np); > > /* Populate the resource table */ > if (num_irq || num_reg) { > @@ -140,7 +147,7 @@ struct platform_device *of_device_alloc(struct > device_node *np, > rc = of_address_to_resource(np, i, res); > WARN_ON(rc); > } > - if (of_irq_to_resource_table(np, res, num_irq) != num_irq) > + if (num_irq && of_irq_to_resource_table(np, res, num_irq) != > num_irq) > pr_debug("not all legacy IRQ resources mapped for %pOFn\n", > np); > }
The root of the issue is that all the resource allocation is done upfront, way before we even have a driver that could potentially deal with this device. This is a potential waste of resource, and it triggers the issue you noticed.
If you delay the resource allocation until there is an actual match with a driver, you could have a per-driver flag telling you whether the IRQ allocation should be performed before the probe() function is called.
M. -- Jazz is not dead. It just smells funny...
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