[PATCH-V4 3/3] ARM: OMAP: Make OMAP clocksource source selection using kernel param

[Jon Hunter]

Hi Vaibhav, Russ,

On 04/26/2012 08:46 AM, Hiremath, Vaibhav wrote:
> On Thu, Apr 26, 2012 at 13:15:18, Russ Dill wrote:
>> On Wed, Apr 25, 2012 at 11:23 PM, Hiremath, Vaibhav <hvaibhav at ti.com> wrote:
>>> On Thu, Apr 26, 2012 at 11:26:09, Russ Dill wrote:
>>>> On Wed, Apr 25, 2012 at 10:42 PM, Hiremath, Vaibhav <hvaibhav at ti.com> wrote:
>>>>> On Thu, Apr 26, 2012 at 10:06:40, Russ Dill wrote:
>>>>>> On Tue, Apr 24, 2012 at 2:45 AM, Vaibhav Hiremath <hvaibhav at ti.com> wrote:
>>>>>>> Current OMAP code supports couple of clocksource options based
>>>>>>> on compilation flag (CONFIG_OMAP_32K_TIMER). The 32KHz sync-timer
>>>>>>> and a gptimer which can run on 32KHz or system clock (e.g 38.4 MHz).
>>>>>>> So there can be 3 options -
>>>>>>>
>>>>>>> 1. 32KHz sync-timer
>>>>>>> 2. Sys_clock based (e.g 13/19.2/26/38.4 MHz) gptimer
>>>>>>> 3. 32KHz based gptimer.
>>>>>>>
> <Snip>
>>>
>>> You mean to say, on Beagleboard it boots up fine. And same fails on EVM?
>>
>>
>> yes
>>
> 
> I am able to reproduce this issue, and it seems the issue is really weird 
> and I am completely clueless here.
> 
> With below patch/change it always works, 100% success. The moment I add 0x10 
> offset to the ioremaped virtual base address, gone...95% of the time it 
> fails.
> I have observed that, the execution always stays at wfi (default_idle) 
> thread. Really strange behavior...and I am clueless now.
> 
>  - The 32k sync timer address space is part of iotable.
>  - The ioremap() internally masks the addr to page aligned addr and gets pfn,
>    At the end, offset is being added. So I don't really understand how is it
>    different than adding offset before and after ioremap().
> 
> 
> Also, this issue is nothing to do with my patch, it also happens with the 
> original code.
> Just add 0x10 offset after ioremap(), and booooooom.... (95% of the time)
> 
> 
> ----------Patch which works (on top of this patch-series)----------
> 
> diff --git a/arch/arm/plat-omap/counter_32k.c b/arch/arm/plat-omap/counter_32k.c
> index 3e3cdab..b0ef8ce 100644
> --- a/arch/arm/plat-omap/counter_32k.c
> +++ b/arch/arm/plat-omap/counter_32k.c
> @@ -90,6 +90,7 @@ int __init omap_init_clocksource_32k(u32 pbase, unsigned long size)
>          * For this to work we must have a static mapping in io.c
>          * for this area
>          */
> +       pbase = pbase + OMAP2_32KSYNCNT_CR_OFF;
>         base = ioremap(pbase, size);

What is size set to in the failing case on the am37xx device? Any chance
we are not mapping enough space?

Cheers
Jon