[PATCH 0/5] OMAP4: cache fixes for 4460
mans.rullgard at linaro.org
Mon Nov 28 00:26:10 UTC 2011
On 27 November 2011 23:36, Siarhei Siamashka
<siarhei.siamashka at gmail.com> wrote:
> On Mon, Nov 28, 2011 at 12:18 AM, Mans Rullgard
> <mans.rullgard at linaro.org> wrote:
>> On 27 November 2011 21:30, Siarhei Siamashka
>> <siarhei.siamashka at gmail.com> wrote:
>>> On Sun, Nov 27, 2011 at 8:18 PM, Woodruff, Richard <r-woodruff2 at ti.com> wrote:
>>>>> From: linaro-dev-bounces at lists.linaro.org [mailto:linaro-dev-
>>>>> bounces at lists.linaro.org] On Behalf Of Mans Rullgard
>>>>> >> Do you have an erratum number for this?
>>>>> > This was very recent BUG and not yet made it to the public errata
>>>>> > numbers. Most likely next PL310 errata update should have
>>>>> > this one documented.
>>>>> Do you have _any_ identifier for it?
>>>> ARM expanded errata 752271 to cover DLF not working till r3p2 in errata version 13.1 (21 Nov 11), 4460 is r3p1-50rel0 and is impacted.
>>> Thanks a lot. Your posts are very informative as usual.
>>> By the way, do you know whether it is safe to use "SCU Speculative
>>> linefills" with Cortex-A9 r2pX and PL310 r3pX?
>>> As a quick and dirty test, it can be enabled in
>>> 'arch/arm/kernel/smp_scu.c' by just setting extra (1 << 3) bit in SCU
>>> Control Register from 'scu_enable' function.
>> The SCU is already enabled when that function runs (don't know what
>> enables it), so you'll need to remove the early return to make any
> Do you mean SCU is enabled and has "SCU Speculative linefills enable"
> bit already set on OMAP4460? Or just SCU is enabled without
> speculative linefills?
On the OMAP4, the SCU is enabled but speculative linefills are not.
To enable speculative linefills, I simply removed the early return
from that function.
> In my case (origenboard),
If talking about a different chip in a thread titled OMAP4, it is
a good idea to mention this.
Be careful. That chip has PL310 r3p0 so it's affected by erratum
729806, "Speculative reads from the Cortex-A9 MPCore processor can cause
> 'scu_enable' function seems to be called
> just once and the value in SCU Control Register is originally
> 0x00000000. So SCU gets enabled without speculative linefills when
> using the current linaro u-boot and kernel. And I thought that
> speculative linefills might be not enabled on purpose. But I guess
> this is actually a question for Samsung folks.
It is off by default in the hardware. That code is shared by all
ARM MPCore system, so it's probably best not to turn it on unless
explicitly requested somehow.
Mans Rullgard / mru
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