[PATCH v3 2/2] OMAP: IOMMU: add support to callback during fault handling

On Thu, Feb 24, 2011 at 5:29 AM, Felipe Balbi [off-list ref] wrote:

On Thu, Feb 24, 2011 at 01:26:05PM +0200, David Cohen wrote:

quoted

On Thu, Feb 24, 2011 at 10:35 AM, Felipe Balbi [off-list ref] wrote:

quoted

Hi,

On Wed, Feb 23, 2011 at 10:09:05PM +0200, Sakari Ailus wrote:

quoted

quoted

In OMAP4 the cortex M3 is a double core processor and as each core is
running they own version of the RTOS we threat them independently. So
our driver which controls the remote processor sees two processor but
both use the same iommu hw. When a iommu fault happens, at this
moment, it is consider as a faltal error and it is no managed to
recover and continue, instead a restart of the processor is needed, if
the fault happens in core0 we need to reset core1 too and vice versa.
if the iommu would support several user callbacks, we can register the
callback which resets core0 and also the callback which resets core1
and treat them as totally independent processors. Also we have an
error event notifier driver, which is only in charge of notifying
error events to userspace, so we would have multiple callbacks we
could do this

The original purpose of the patch, as far as I understand, is to allow
getting useful information for debugging purposes should an iommu fault
happen.

Also, I'm not sure it's necessarily a good idea to just go and reset
the M3 cores in case an iommu fault happens --- this is very probably a
grave bug in the software running on those M3s. It should be fixed
instead of just hiding it. There will be consequences to host side as

I have to agree here. Besides the fact that multiple callbacks is
outside the scope of this patch.

This patch is already acked. What about leave it as it is and discuss
multiple callbacks before release a new patch to support it?

fine by me ;-)

Ok, maybe it was too late to change it, due to it is already acked, I
just wanted to avoid change isr here and then change it on other
patch. it is ok then.

Regards,
Fernando.

--
balbi