Re: [RFC PATCH] of: platform: Skip mapping of interrupts in of_device_alloc()
From: Marc Zyngier <maz@kernel.org>
Date: 2021-12-09 08:07:19
Also in:
linux-renesas-soc, lkml
On 2021-12-09 00:10, Lad Prabhakar wrote:
quoted hunk ↗ jump to hunk
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/ (local) 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(structdevice_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(structdevice_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.
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+ 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(structdevice_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...