[PATCH v3 2/2] OMAP: IOMMU: add support to callback during fault handling
Guzman Lugo, Fernando
fernando.lugo at ti.com
Thu Feb 24 12:58:13 EST 2011
On Thu, Feb 24, 2011 at 5:29 AM, Felipe Balbi <balbi at ti.com> wrote:
> On Thu, Feb 24, 2011 at 01:26:05PM +0200, David Cohen wrote:
>> On Thu, Feb 24, 2011 at 10:35 AM, Felipe Balbi <balbi at ti.com> wrote:
>> > Hi,
>> > On Wed, Feb 23, 2011 at 10:09:05PM +0200, Sakari Ailus wrote:
>> >> > 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.
More information about the linux-arm-kernel