linux-kernel - Re: Using irq-crossbar.c

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Date:	Thu, 16 Jun 2016 14:39:58 +0200
From:	Sebastian Frias <sf84@...oste.net>
To:	Marc Zyngier <marc.zyngier@....com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Mason <slash.tmp@...e.fr>,
	Måns Rullgård <mans@...sr.com>
Subject: Re: Using irq-crossbar.c

Hi Marc,

On 06/14/2016 06:39 PM, Sebastian Frias wrote:
> On 06/14/2016 06:37 PM, Sebastian Frias wrote:
>>>>> Also, without seeing the code,
>>>>> it is pretty difficult to make any meaningful comment...
>>>>
>>>> Base code is either 4.7rc1 or 4.4.
>>>> The irq-crossbar code is not much different from TI, but you can find it attached.
>>>
>>> Please post it separately (and inline), the email client I have here
>>> makes it hard to review attached patches.
>>
>> Ok, I'll post it in a separate email and inline.
>>
> 
> Here it goes:
> 
> 

 <snipped code>

> IRQCHIP_DECLARE(tangox_intc, "sigma,smp-irq-mux", tangox_of_irq_mux_init);
> 
> 

I have tested the code, and aside from the missing #interrupt-cells in the DT that you pointed out, it seems it is working (devices using IRQ appear functional), here's some log:

tangox_irq_mux_domain_translate(): domain 0xcf805000
tangox_irq_mux_domain_translate(): hwirq 1 (0x1) type 4 (0x4)
tangox_irq_mux_domain_alloc(): domain 0xcf805000, virq 18 (0x12) nr_irqs 1
tangox_allocate_gic_irq(): domain 0xcf805000, virq 18 (0x12) hwirq 1 (0x1)
tangox_setup_irq_route(): route irq  1 (@ 0xf006f804) => irq 23
tangox_irq_mux_domain_translate(): domain 0xcf805000
tangox_irq_mux_domain_translate(): hwirq 38 (0x26) type 4 (0x4)
tangox_irq_mux_domain_alloc(): domain 0xcf805000, virq 19 (0x13) nr_irqs 1
tangox_allocate_gic_irq(): domain 0xcf805000, virq 19 (0x13) hwirq 38 (0x26)
tangox_setup_irq_route(): route irq 38 (@ 0xf006f898) => irq 22
tangox_irq_mux_domain_translate(): domain 0xcf805000
tangox_irq_mux_domain_translate(): hwirq 67 (0x43) type 4 (0x4)
tangox_irq_mux_domain_alloc(): domain 0xcf805000, virq 20 (0x14) nr_irqs 1
tangox_allocate_gic_irq(): domain 0xcf805000, virq 20 (0x14) hwirq 67 (0x43)
tangox_setup_irq_route(): route irq 67 (@ 0xf006f90c) => irq 21

Since irq-tango_v2.c is similar to irq-crossbar.c from TI (since it is based on it), I was wondering what is the policy or recommendation in such cases?
Should I attempt to merge the code (mainly the way to set up the registers) on irq-crossbar.c or should we consider irq-tango_v2.c to live its own life?

NOTE: IMHO, irq-crossbar.c could benefit from clearer names for some DT properties, because "max_irqs" and "max-crossbar-sources" are not straight forward names for "mux_outputs" and "mux_inputs" (respectively)

NOTE2: current irq-tango_v2.c code still has a 24 IRQ limitation since it is not using any API that would allow it to setup IRQ sharing.

Thanks in advance.
Best regards,

Sebastian