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

[Marc Zyngier <marc.zyngier@arm.com>]

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...