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SubjectRe: [PATCH V7] ACPI, PCI, irq: support IRQ numbers greater than 256
Hi Sinan,

On Mon, Nov 30, 2015 at 06:39:01PM -0500, Sinan Kaya wrote:
> The ACPI compiler uses the extended format when used interrupt numbers
> are greater than 15. The extended IRQ is 32 bits according to the ACPI
> spec. The code supports parsing the extended interrupt numbers. However,
> due to used data structure type; the code silently truncates interrupt
> numbers greater than 256.
>
> This patch changes the interrupt number type to 32 bits and places an
> upper limit of 1020 as possible interrupt id. 1020 is the maximum
> interrupt ID that can be assigned to an ARM SPI interrupt according to
> ARM architecture.
>
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> ---
> drivers/acpi/pci_link.c | 30 +++++++++++++++++++++++++-----
> 1 file changed, 25 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
> index 7c8408b..faa37cd 100644
> --- a/drivers/acpi/pci_link.c
> +++ b/drivers/acpi/pci_link.c
> @@ -4,6 +4,7 @@
> * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
> * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
> * Copyright (C) 2002 Dominik Brodowski <devel@brodo.de>
> + * Copyright (c) 2015, The Linux Foundation. All rights reserved.
> *
> * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> *
> @@ -47,6 +48,14 @@ ACPI_MODULE_NAME("pci_link");
> #define ACPI_PCI_LINK_FILE_STATUS "state"
> #define ACPI_PCI_LINK_MAX_POSSIBLE 16
>
> +/*
> + * 1020 is the maximum interrupt ID that can be assigned to
> + * an ARM SPI interrupt according to ARM architecture.
> + */
> +#define ACPI_MAX_IRQS 1020
> +#define ACPI_MAX_ISA_IRQ 16

Not sure whether you saw my earlier response about this:

ACPI_MAX_IRQS is only used to size the acpi_irq_penalty[] table (and
after your patch, to validate IRQ numbers from ACPI). But I think
the acpi_irq_penalty[] table is a design we've outgrown. I *think*
we only care about penalties for IRQs 0-15, so even a 256-entry
table is more than we need.

If we could make acpi_irq_penalty[] a fixed size of 16 entries or
replace it with a linked list, I think we could get rid of
ACPI_MAX_IRQS completely. Then the validation checks you add below
would be unnecessary and we could handle any interrupt number
supplied from ACPI.

I think it would be really nice to get rid of the arbitrary maximum
interrupt ID (1020).

Bjorn

> +
> +
> static int acpi_pci_link_add(struct acpi_device *device,
> const struct acpi_device_id *not_used);
> static void acpi_pci_link_remove(struct acpi_device *device);
> @@ -67,12 +76,12 @@ static struct acpi_scan_handler pci_link_handler = {
> * later even the link is disable. Instead, we just repick the active irq
> */
> struct acpi_pci_link_irq {
> - u8 active; /* Current IRQ */
> + u32 active; /* Current IRQ */
> u8 triggering; /* All IRQs */
> u8 polarity; /* All IRQs */
> u8 resource_type;
> u8 possible_count;
> - u8 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
> + u32 possible[ACPI_PCI_LINK_MAX_POSSIBLE];
> u8 initialized:1;
> u8 reserved:7;
> };
> @@ -147,6 +156,13 @@ static acpi_status acpi_pci_link_check_possible(struct acpi_resource *resource,
> p->interrupts[i]);
> continue;
> }
> + if (p->interrupts[i] >= ACPI_MAX_IRQS) {
> + dev_warn(&link->device->dev,
> + "Ignoring IRQ(%d) as it exceeds max(%d)\n",
> + p->interrupts[i],
> + ACPI_MAX_IRQS - 1);
> + continue;
> + }
> link->irq.possible[i] = p->interrupts[i];
> link->irq.possible_count++;
> }
> @@ -279,6 +295,13 @@ static int acpi_pci_link_get_current(struct acpi_pci_link *link)
> result = -ENODEV;
> }
>
> + if (irq >= ACPI_MAX_IRQS) {
> + dev_err(&link->device->dev,
> + "Ignoring IRQ(%d) as it exceeds max(%d)\n",
> + irq, ACPI_MAX_IRQS - 1);
> + result = -ENODEV;
> + goto end;
> + }
> link->irq.active = irq;
>
> ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Link at IRQ %d \n", link->irq.active));
> @@ -437,9 +460,6 @@ static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
> * enabled system.
> */
>
> -#define ACPI_MAX_IRQS 256
> -#define ACPI_MAX_ISA_IRQ 16
> -
> #define PIRQ_PENALTY_PCI_AVAILABLE (0)
> #define PIRQ_PENALTY_PCI_POSSIBLE (16*16)
> #define PIRQ_PENALTY_PCI_USING (16*16*16)
> --
> Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>
> --
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