Subject: Re: regression: OMAP4 (next-20141204) (bisect to: ARM: 8208/1: l2c: Refactor the driver to use commit-like)

From: Marek Szyprowski <[email-masked]>
Date: Wed, 10 Dec 2014 10:42:33 +0100

Hello,

On 2014-12-09 17:57, Nishanth Menon wrote:
> On 10:13-20141205, Nishanth Menon wrote:
>> On 12/05/2014 10:10 AM, Nishanth Menon wrote:
>>> next-20141204 fails to boot, but next-20141203 boots fine with
>>> omap2plus_defconfig.
>>>
>>> Panda-ES(4460):
>>> https://github.com/nmenon/kernel-test-logs/blob/next-20141204/omap2plus_defconfig/pandaboard-es.txt
>>> Panda(4430):
>>> https://github.com/nmenon/kernel-test-logs/blob/next-20141204/omap2plus_defconfig/pandaboard-vanilla.txt
>>>
>>> at the point of hang (JTAG):
>>>   pandaboard-es:
>>> 	cpu0: http://slexy.org/view/s2eIFqkRd5
>>> 	cpu1: http://slexy.org/view/s2Tysb6gpL
>>>
>>> Case #1:
>>> Disabling CPUIDLE allows boot to proceed. there does not seem to have
>>> been any change in drivers/cpuidle and arch/arm/mach-omap2 w.r.t this.
>>>
>>> Case #2: Reverting the following allows boot.
>>>
>>>  From next-20141204
>>> 10df7d5 ARM: 8211/1: l2c: Add support for overriding prefetch settings
>>> revert this  -> boot still fails
>>>
>>> d42ced0 ARM: 8210/1: l2c: Get outer cache .write_sec callback from
>>> mach_desc only if not NULL
>>> revert this  -> boot still fails
>>>
>>> 46b9af8 ARM: 8209/1: l2c: Add interface to ask hypervisor to configure L2C
>>> revert this  -> boot still fails
>>>
>>> c94e325 ARM: 8208/1: l2c: Refactor the driver to use commit-like
>>> revert this  -> boot passed (first bad commit).
>>>
>>>
>> + linux-samsung soc and updated Thomaz's mail ID (gmail now).
> Spend a few mins trying to track this down and it does look like commit
> c94e325 does a kmemdup for the data as part of l2x0_of_init->__l2c_init
>
> This fails since the invocation is in early_init. doing it a bit later
> as the following hack makes it work
> diff --git a/arch/arm/mach-omap2/board-generic.c b/arch/arm/mach-omap2/board-generic.c
> index 608079a..0bc6bd9 100644
> --- a/arch/arm/mach-omap2/board-generic.c
> +++ b/arch/arm/mach-omap2/board-generic.c
> @@ -170,12 +170,19 @@ static const char *const omap4_boards_compat[] __initconst = {
>   	NULL,
>   };
>   
> +
> +static void tmp_init_irq(void)
> +{
> +	omap_l2_cache_init();
> +	omap_gic_of_init();
> +}
> +
>   DT_MACHINE_START(OMAP4_DT, "Generic OMAP4 (Flattened Device Tree)")
>   	.reserve	= omap_reserve,
>   	.smp		= smp_ops(omap4_smp_ops),
>   	.map_io		= omap4_map_io,
>   	.init_early	= omap4430_init_early,
> -	.init_irq	= omap_gic_of_init,
> +	.init_irq	= tmp_init_irq,
>   	.init_machine	= omap_generic_init,
>   	.init_late	= omap4430_init_late,
>   	.init_time	= omap4_local_timer_init,
> diff --git a/arch/arm/mach-omap2/io.c b/arch/arm/mach-omap2/io.c
> index 03cbb16..f97847d 100644
> --- a/arch/arm/mach-omap2/io.c
> +++ b/arch/arm/mach-omap2/io.c
> @@ -627,7 +627,6 @@ void __init omap4430_init_early(void)
>   	omap44xx_clockdomains_init();
>   	omap44xx_hwmod_init();
>   	omap_hwmod_init_postsetup();
> -	omap_l2_cache_init();
>   	omap_clk_soc_init = omap4xxx_dt_clk_init;
>   }
>   

Please note that am43xx_init_early() also calls omap_l2_cache_init(),
so similar fix is needed for "Generic AM43 (Flattened Device Tree)"
machines.

I've briefly looked how the initialization is done on various omap
platforms, but I don't see the good generic place for omap_l2_cache_init().
IMHO the best solution will be to completely switch to generic/common l2c
initialization and provide ".l2c_aux_val" and ".l2c_aux_mask" in machine
descriptor. For the time being something like proposed above can be used.

I assume that now it won't be possible to get l2c patches back to -next,
so I will resend them (again...) with the omap related fix.

> diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c
> index e5948c5..0ca90db 100644
> --- a/arch/arm/mm/cache-l2x0.c
> +++ b/arch/arm/mm/cache-l2x0.c
> @@ -848,8 +848,11 @@ static int __init __l2c_init(const struct l2c_init_data *data,
>   	 * context from callers can access the structure.
>   	 */
>   	l2x0_data = kmemdup(data, sizeof(*data), GFP_KERNEL);
> -	if (!l2x0_data)
> +	if (!l2x0_data) {
> +		pr_err("%s no mem %d\n", __func__, sizeof(*data));
> +		dump_stack();
>   		return -ENOMEM;
> +	}
>   
>   	/*
>   	 * Sanity check the aux values.  aux_mask is the bits we preserve
> @@ -1647,6 +1650,7 @@ int __init l2x0_of_init(u32 aux_val, u32 aux_mask)
>   	struct device_node *np;
>   	struct resource res;
>   	u32 cache_id, old_aux;
> +	int r;
>   
>   	np = of_find_matching_node(NULL, l2x0_ids);
>   	if (!np)
> @@ -1693,6 +1697,8 @@ int __init l2x0_of_init(u32 aux_val, u32 aux_mask)
>   	else
>   		cache_id = readl_relaxed(l2x0_base + L2X0_CACHE_ID);
>   
> -	return __l2c_init(data, aux_val, aux_mask, cache_id);
> +	r = __l2c_init(data, aux_val, aux_mask, cache_id);
> +	pr_err("%s: %d\n", __func__, r);
> +	return r;
>   }
>

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland