Re: [PATCH v4 4/5] PCI: iproc: Add iProc PCIe MSI support

[Ray Jui]

On 12/2/2015 6:30 AM, Hauke Mehrtens wrote:
> On 11/27/2015 06:37 PM, 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>
> > ---
> >   drivers/pci/host/Kconfig               |   9 +
> >   drivers/pci/host/Makefile              |   1 +
> >   drivers/pci/host/pcie-iproc-bcma.c     |   1 +
> >   drivers/pci/host/pcie-iproc-msi.c      | 675 +++++++++++++++++++++++++++++++++
> >   drivers/pci/host/pcie-iproc-platform.c |   1 +
> >   drivers/pci/host/pcie-iproc.c          |  26 ++
> >   drivers/pci/host/pcie-iproc.h          |  23 +-
> >   7 files changed, 734 insertions(+), 2 deletions(-)
> >   create mode 100644 drivers/pci/host/pcie-iproc-msi.c
>
> .....
> >   int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res);
> >   int iproc_pcie_remove(struct iproc_pcie *pcie);
> >
> > +#ifdef CONFIG_PCI_MSI
> > +int iproc_msi_init(struct iproc_pcie *pcie, struct device_node *node);
> > +void iproc_msi_exit(struct iproc_pcie *pcie);
> > +#else
> > +static inline int iproc_msi_init(struct iproc_pcie *pcie,
> > +				 struct device_node *node)
> > +{
> > +	return -ENODEV;
> > +}
> > +static void iproc_msi_exit(struct iproc_pcie *pcie)
>
> Please use static inline here.

Right. Will fix. Thanks!

> > +{
> > +}
> > +#endif
> > +
> >   #endif /* _PCIE_IPROC_H */
>
> Hauke

Ray
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