On 04/12/15 17:35, Ray Jui wrote: > This patch adds PCIe MSI support for both PAXB and PAXC interfaces on > all iProc based platforms > > The iProc PCIe MSI support deploys an event queue based implementation. > Each event queue is serviced by a GIC interrupt and can support up to 64 > MSI vectors. Host memory is allocated for the event queues, and each event > queue consists of 64 word-sized entries. MSI data is written to the > lower 16-bit of each entry, whereas the upper 16-bit of the entry is > reserved for the controller for internal processing > > Each event queue is tracked by a head pointer and tail pointer. Head > pointer indicates the next entry in the event queue to be processed by > the driver and is updated by the driver after processing is done. > The controller uses the tail pointer as the next MSI data insertion > point. The controller ensures MSI data is flushed to host memory before > updating the tail pointer and then triggering the interrupt > > MSI IRQ affinity is supported by evenly distributing the interrupts to > each CPU core. MSI vector is moved from one GIC interrupt to another in > order to steer to the target CPU > > Therefore, the actual number of supported MSI vectors is: > > M * 64 / N > > where M denotes the number of GIC interrupts (event queues), and N > denotes the number of CPU cores > > This iProc event queue based MSI support should not be used with newer > platforms with integrated MSI support in the GIC (e.g., giv2m or > gicv3-its) > > Signed-off-by: Ray Jui <rjui@xxxxxxxxxxxx> > Reviewed-by: Anup Patel <anup.patel@xxxxxxxxxxxx> > Reviewed-by: Vikram Prakash <vikramp@xxxxxxxxxxxx> > Reviewed-by: Scott Branden <sbranden@xxxxxxxxxxxx> Good thing I didn't reply on v4! Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx> M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
