Re: [PATCH v6 4/8] ARM: Add .init_platform() callback to machine descriptor

Marc Zyngier
2013-06-21T10:24:59Z

On 21/06/13 01:35, Tomasz Figa wrote:

Hi Tomasz,

> Most ARM platforms have parts that should be initialized as early as
> possible, which usually means as soon as memory management (kmalloc,
> ioremap) starts to work,
>
> However, currently there is no appropriate callback in machine_desc
> struct to use for such initialization and platforms tend to stuff things
> up .init_irq() and .init_time() callbacks.
>
> Since all the DT-based platforms are going towards generic IRQ and time
> initialization (using irqchip_init and clocksource_of_init) and current
> code assumes that if custom callbacks are not provided in machine_desc
> then generic ones should be used, this problem has become a bit more
> inconvenient.
>
> This patch tries to solve this issue by introducing new callback called
> .init_platform(), where any custom low level initialization of platform
> can be done safely.
>
> Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
> ---
> arch/arm/include/asm/mach/arch.h | 1 +
> arch/arm/kernel/irq.c | 3 +++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
> index 308ad7d..b2f4d11 100644
> --- a/arch/arm/include/asm/mach/arch.h
> +++ b/arch/arm/include/asm/mach/arch.h
> @@ -46,6 +46,7 @@ struct machine_desc {
> void (*reserve)(void);/* reserve mem blocks */
> void (*map_io)(void);/* IO mapping function */
> void (*init_early)(void);
> + void (*init_platform)(void);
> void (*init_irq)(void);
> void (*init_time)(void);
> void (*init_machine)(void);
> diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
> index 9723d17..61e2000 100644
> --- a/arch/arm/kernel/irq.c
> +++ b/arch/arm/kernel/irq.c
> @@ -115,6 +115,9 @@ EXPORT_SYMBOL_GPL(set_irq_flags);
>
> void __init init_IRQ(void)
> {
> + if (machine_desc->init_platform)
> + machine_desc->init_platform();
> +
> if (IS_ENABLED(CONFIG_OF) && !machine_desc->init_irq)
> irqchip_init();
> else

To me, this new hook is strictly equivalent to init_irq. What do we gain
exactly? I didn't think init_irq was going away...

I know init_irq is not pretty, and we tend to overload it with other
stuff, but I don't really see the point of adding a new callback that
has the exact same properties.

M.
--
Jazz is not dead. It just smells funny...