On Thursday 08 January 2009, Kenji Kaneshige wrote: > Rafael J. Wysocki wrote: > > From: Rafael J. Wysocki <rjw@xxxxxxx> > > > > If MSI-X interrupt mode is used by the PCI Express port driver, too > > many vectors are allocated and it is not ensured that the right > > vectors will be used for various services. Namely, the PCI Express > > specification states that both PCI Express native PME and PCI Express > > hotplug will always use the same MSI or MSI-X message for signalling > > interrupts, which implies that the same vector will be used by both > > of them. Also, the VC service does not use interrupts at all. > > Moreover, is not clear which of the vectors allocated by > > pci_enable_msix() will be used for PME and hotplug and which of them > > will be used for AER if all of these services are configured. > > > > For these reasons, rework the allocation of interrupts for PCI > > Express ports so that at most two vectors are allocated and ensure > > that the right vector will be used for the right purpose. > > > > Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx> > > --- > > drivers/pci/pcie/portdrv.h | 1 > > drivers/pci/pcie/portdrv_core.c | 155 +++++++++++++++++++++++++++++----------- > > 2 files changed, 117 insertions(+), 39 deletions(-) > > > > Index: linux-2.6/drivers/pci/pcie/portdrv.h > > =================================================================== > > --- linux-2.6.orig/drivers/pci/pcie/portdrv.h > > +++ linux-2.6/drivers/pci/pcie/portdrv.h > > @@ -25,6 +25,7 @@ > > #define PCIE_CAPABILITIES_REG 0x2 > > #define PCIE_SLOT_CAPABILITIES_REG 0x14 > > #define PCIE_PORT_DEVICE_MAXSERVICES 4 > > +#define PORT_MSI_VECTOR_MASK 0x1f > > > > #define get_descriptor_id(type, service) (((type - 4) << 4) | service) > > > > Index: linux-2.6/drivers/pci/pcie/portdrv_core.c > > =================================================================== > > --- linux-2.6.orig/drivers/pci/pcie/portdrv_core.c > > +++ linux-2.6/drivers/pci/pcie/portdrv_core.c > > @@ -30,55 +30,120 @@ static void release_pcie_device(struct d > > } > > > > /** > > + * fix_up_vectors - ensure the right ordering of MSI-X interrupt vectors > > + * @dev: PCI Express port that is going to use the vectors > > + * @vectors: Array of interrupt vectors to check (2 entries) > > + * > > + * Return value: > > + * 0 on success, error code if the values read from config registers are not as > > + * expected > > + * > > + * If this function is called, we are going to use two interrupt vectors which > > + * may be different, but we have to make sure they are in the right order such > > + * that the vector to be used for PME and hotplug signalling is the first one. > > + * > > + * NOTE: The assumption here is that MSI message offset (with respect to the > > + * base Message Data) equal to N corresponds to index N in the array of vectors > > + * returned by pci_enable_msix(). > > + */ > > I've posted the similar patch recently, which doesn't have this > assumption. Actually, this assumption is in agreement with PCI Express Base Specification 2.0, which very clearly states in Section 7.8.2 that: "[...] Interrupt Message Number – This field indicates which MSI/MSI-X vector is used for the interrupt message generated in association with any of the status bits of this Capability structure. [...] For MSI-X, the value in this field indicates which MSI-X Table entry is used to generate the interrupt message. The entry must be one of the first 32 entries even if the Function implements more than 32 entries. For a given MSI-X implementation, the entry must remain constant." Well, I have to update the comment. :-) > Please take a look. > > http://marc.info/?l=linux-pci&m=122992792507715&w=2 OK, thanks. I can easily change my patch to follow this behavior, although I don't really think it's necessary given the above. > NOTE: I've confirmed MSI and INTx still work with my patch, but it > is not tested on the machine with MSI-X capable port, since I don't > have such environment. I also have tested my patch with both MSI and INTx, but I also don't have MSI-X capable root ports in any of my test boxes. Thanks, Rafael -- 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
