[PATCH] arm: omap: ratelimit omap_l3_smx error log spam

[Shilimkar, Santosh]

On Mon, Aug 27, 2012 at 4:26 PM, Aaro Koskinen <aaro.koskinen at iki.fi> wrote:
> On Mon, Aug 27, 2012 at 03:12:07PM -0700, Shilimkar, Santosh wrote:
>> On Mon, Aug 27, 2012 at 3:02 PM, Aaro Koskinen <aaro.koskinen at iki.fi> wrote:
>> > Hi,
>> >
>> > On Mon, Aug 27, 2012 at 02:35:57PM -0700, Shilimkar, Santosh wrote:
>> >> > -       pr_err("%s seen by %s %s at address %x\n",
>> >> > +       pr_err_ratelimited("%s seen by %s %s at address %x\n",
>> >> >                         omap3_l3_code_string(code),
>> >> >                         omap3_l3_initiator_string(initid),
>> >> >                         multi ? "Multiple Errors" : "", address);
>> >> > -       WARN_ON(1);
>> >> > +       WARN_ON_ONCE(1);
>> >> >
>> >> The issue needs to be fixed instead of WARN_ON_ONCE() and then
>> >> just moving ahead. Interconnect in bad states is really bad state and you
>> >> won't have reliable operations post that on SOC.
>> >
>> > How printing megabytes of identical stack traces helps anything?
>> >
>> It just says repeatedly and  loudly... Fix the issue :-)
>>
>> > This has been there always (since the L3 driver was added) on every boot
>> > with N950/N9 (which BTW are HS devices, not sure if that has anything
>> > to do with it). There is no apparent effect on device functionality,
>> > at least nothing unusual has been observed...
>> >
>> I assumed this is secure device when I saw the SRAM memset is causing the
>> issue.
>>
>> > Is there any documentation how to interpret and debug this error report?
>> >
>> The issue could be, there is memset tried on Secure portion of SRAM or
>> CPU speculatively accessed adjacent SRAM region of public SRAM which
>> is secure and hence the error.
>
> Thanks, that makes sense.
>
>> If you just bypass the SRAM init [1], does the issue go away ?
>
> I tried bypassing the whole SRAM init, but the device does not seem to
> boot up at all.
>
> If I comment out the memset alone, then it boots and the issue is gone:
>
> +#if 0
>         memset_io(omap_sram_base + SRAM_BOOTLOADER_SZ, 0,
>                   omap_sram_size - SRAM_BOOTLOADER_SZ);
> +#endif
>
Good. So the issue is indeed direct or indirect access to the secure SRAM.
As security can dynamically resize the secure RAM size it is even harder
to fix this issue properly. One easier way to deal with the issue is map only
needed SRAM and leave rest for security.

For now, Can you check if reducing the size of the SRAM in init is helping you
to get way with the issue. Sorry it might need few iterations for you to get
a working SRAM size.

Regards
Santosh