From mboxrd@z Thu Jan 1 00:00:00 1970 From: sakari.ailus@maxwell.research.nokia.com (Sakari Ailus) Date: Wed, 23 Feb 2011 22:09:05 +0200 Subject: [PATCH v3 2/2] OMAP: IOMMU: add support to callback during fault handling In-Reply-To: References: <1297884951-3019-1-git-send-email-dacohen@gmail.com> <1297884951-3019-3-git-send-email-dacohen@gmail.com> Message-ID: <4D656961.7080105@maxwell.research.nokia.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Guzman Lugo, Fernando wrote: > Hi, Hi Fernando, > 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 well, won't there? > iommu <---- register fault callback for error notify driver > > instead of > > iommu <--- register fault callback for remote processor driver > <----register fault event for error notify driver. > > with that, we remove one dependency of the errornotify driver. I suppose this is not in mainline? Regards, -- Sakari Ailus sakari.ailus at maxwell.research.nokia.com