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SubjectRe: [PATCH 5/8] PCI PCIe portdrv: Fix allocation of interrupts
Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
>
> 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@sisk.pl>
> ---
> 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. Please take a look.

http://marc.info/?l=linux-pci&m=122992792507715&w=2

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.

Thanks,
Kenji Kaneshige



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