[PATCH] staging: tidspbridge: MMU2 registers are limited to 32-bit data access

Ramirez Luna, Omar omar.ramirez at ti.com
Wed Oct 19 18:46:18 UTC 2011


Hi Vladimir,

On Wed, Oct 19, 2011 at 11:45 AM, Vladimir Zapolskiy <vz at mleia.com> wrote:
> According to OMAP3 TRM access to MMU registers shall be strictly 32-bit
> aligned. Sometimes non-linefetch aborts are observed while flushing
> TLB, and this fix is intended to get them extincted.

Looks good to be included to avoid confusions about the accesses to
mmu registers, however...

Lately I have seen these aborts, but they don't seem to be related to
the wrong bit size accesses. The TRM indeed forbids other than 32-bit
accesses as it can cause register corruption but doesn't specify if
the corrupted register is the one being accessed, the whole module
registers or else.

Usually the behavior seen during this error, in my case, is that
previous transitions to hibernation fail, and this ultimately leads to
an L3 timeout, but the error has originated in the DSP, the unhandled
abort panic is just another error to the pile. The solution found, was
to move code from the DSP originating a circle path in the L3 (used to
calculate the warm boot address from a dsp va to a pa) causing the
Hibernate failed error. This fix requires a patched baseimage.

>
> Signed-off-by: Vladimir Zapolskiy <vz at mleia.com>
> Cc: Omar Ramirez Luna <omar.ramirez at ti.com>

For above mentioned reasons, it would be good to change the
description and removing this as a possible fix to the aborts. BTW,
I'm still able to see the aborts with your patch.

After the description change please feel free to add my ack.

Regards,

Omar



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