linux-kernel - Re: [PATCH V12 01/10] APCI: irq: Add support for multiple GSI domains

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Message-ID: <87k09ipfe2.wl-maz@kernel.org>
Date:   Wed, 15 Jun 2022 08:14:29 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Jianmin Lv <lvjianmin@...ngson.cn>
Cc:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        Hanjun Guo <guohanjun@...wei.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>
Subject: Re: [PATCH V12 01/10] APCI: irq: Add support for multiple GSI domains

On Wed, 15 Jun 2022 07:07:21 +0100,
Jianmin Lv <lvjianmin@...ngson.cn> wrote:
> 
> From: Marc Zyngier <maz@...nel.org>
> 
> In an unfortunate departure from the ACPI spec, the LoongArch
> architecture split its GSI space across multiple interrupt
> controllers.
> 
> In order to be able to reuse sthe core code and prevent
> architectures from reinventing an already square wheel, offer
> the arch code the ability to register a dispatcher function
> that will return the domain fwnode for a given GSI.
> 
> The ARM GIC drivers are updated to support this (with a single
> domain, as intended).
> 
> Co-developed-by: Jianmin Lv <lvjianmin@...ngson.cn>

I don't think this tag is appropriate here.

> Signed-off-by: Marc Zyngier <maz@...nel.org>
> Cc: Hanjun Guo <guohanjun@...wei.com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Signed-off-by: Jianmin Lv <lvjianmin@...ngson.cn>
> ---
>  drivers/acpi/irq.c           | 40 +++++++++++++++++++++++-----------------
>  drivers/irqchip/irq-gic-v3.c | 18 ++++++++++++------
>  drivers/irqchip/irq-gic.c    | 18 ++++++++++++------
>  include/linux/acpi.h         |  2 +-
>  4 files changed, 48 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
> index c68e694..b7460ab 100644
> --- a/drivers/acpi/irq.c
> +++ b/drivers/acpi/irq.c
> @@ -12,7 +12,7 @@
>  
>  enum acpi_irq_model_id acpi_irq_model;
>  
> -static struct fwnode_handle *acpi_gsi_domain_id;
> +static struct fwnode_handle *(*acpi_get_gsi_domain_id)(u32 gsi);
>  
>  /**
>   * acpi_gsi_to_irq() - Retrieve the linux irq number for a given GSI
> @@ -26,10 +26,7 @@
>   */
>  int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
>  {
> -	struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
> -							DOMAIN_BUS_ANY);
> -
> -	*irq = irq_find_mapping(d, gsi);
> +	*irq = acpi_register_gsi(NULL, gsi, -1, -1);

What is this?

- This wasn't part of my initial patch, and randomly changing patches
  without mentioning it isn't acceptable

- you *cannot* trigger a registration here, as this isn't what the API
  advertises

- what makes you think that passing random values (NULL, -1... )to
  acpi_register_gsi() is an acceptable thing to do?

The original patch had:

@@ -26,8 +26,10 @@ static struct fwnode_handle *acpi_gsi_domain_id;
   */
  int acpi_gsi_to_irq(u32 gsi, unsigned int *irq)
  {
-	struct irq_domain *d = irq_find_matching_fwnode(acpi_gsi_domain_id,
-							DOMAIN_BUS_ANY);
+	struct irq_domain *d;
+
+	d = irq_find_matching_fwnode(acpi_get_gsi_domain_id(gsi),
+				     DOMAIN_BUS_ANY);
    	*irq = irq_find_mapping(d, gsi);
  	/*

and I don't think it needs anything else. If something breaks, let's
discuss it, but don't abuse the API nor the fact that I usually don't
review my own patches to sneak things in...

	M.

-- 
Without deviation from the norm, progress is not possible.