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SubjectRe: [PATCH v2] PCI/AER: enable SERR# forwarding for bridges and switches
Hi Sinan,

On Wed, Dec 02, 2015 at 11:49:56AM -0500, Sinan Kaya wrote:
> A PCIe card behind a switch is unable to report its errors when SERR#
> forwarding is not enabled on the PCIe# switch's secondary interface
> according to the spec. This patch enables SERR# forwarding when the PCI
> header type is bridge.
>
> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>

I'm sitting on this for the moment because if you have _HPP, it seems
like that should be enough to get SERR# forwarding turned on, and if
it's not, I'd like to understand why. So no hurry, but I'm waiting on
your investigation.

Bjorn

> ---
> drivers/pci/pcie/aer/aerdrv_core.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
> index 9803e3d..f248c17 100644
> --- a/drivers/pci/pcie/aer/aerdrv_core.c
> +++ b/drivers/pci/pcie/aer/aerdrv_core.c
> @@ -37,21 +37,53 @@ module_param(nosourceid, bool, 0);
>
> int pci_enable_pcie_error_reporting(struct pci_dev *dev)
> {
> + u8 header_type;
> +
> if (pcie_aer_get_firmware_first(dev))
> return -EIO;
>
> if (!pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ERR))
> return -EIO;
>
> + pci_read_config_byte(dev, PCI_HEADER_TYPE, &header_type);
> +
> + /* needs to be a bridge/switch */
> + if (header_type == PCI_HEADER_TYPE_BRIDGE) {
> + u16 control;
> +
> + /*
> + * A switch will not forward ERR_ messages coming from an
> + * endpoint if SERR# forwarding is not enabled.
> + * AER driver is checking the errors at the root only.
> + */
> + pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &control);
> + control |= PCI_BRIDGE_CTL_SERR;
> + pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control);
> + }
> +
> return pcie_capability_set_word(dev, PCI_EXP_DEVCTL, PCI_EXP_AER_FLAGS);
> }
> EXPORT_SYMBOL_GPL(pci_enable_pcie_error_reporting);
>
> int pci_disable_pcie_error_reporting(struct pci_dev *dev)
> {
> + u8 header_type;
> +
> if (pcie_aer_get_firmware_first(dev))
> return -EIO;
>
> + pci_read_config_byte(dev, PCI_HEADER_TYPE, &header_type);
> +
> + /* needs to be a bridge/switch */
> + if (header_type == PCI_HEADER_TYPE_BRIDGE) {
> + u16 control;
> +
> + /* clear serr forwarding */
> + pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &control);
> + control &= ~PCI_BRIDGE_CTL_SERR;
> + pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control);
> + }
> +
> return pcie_capability_clear_word(dev, PCI_EXP_DEVCTL,
> PCI_EXP_AER_FLAGS);
> }
> --
> Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>
> --
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