On 9/2/22 4:35 PM, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
>
> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> ---
> drivers/pci/pcie/ptm.c | 34 +++++++++++++++++++++++++++-------
> 1 file changed, 27 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/pci/pcie/ptm.c b/drivers/pci/pcie/ptm.c
> index b6a417247ce3..ad283818f37b 100644
> --- a/drivers/pci/pcie/ptm.c
> +++ b/drivers/pci/pcie/ptm.c
> @@ -167,11 +167,11 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> if (!pos)
> return -EINVAL;
>
> - pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
> - if (!(cap & PCI_PTM_CAP_REQ))
> - return -EINVAL;
> -
May be saving PCI_PTM_CAP_REQ enabled state here and using it below only for
endpoints checks will reduce the code duplication?
> /*
> + * Root Ports and Switch Upstream Ports have been configured
> + * by pci_ptm_init(), so preserve their PCI_PTM_CTRL_ROOT and
> + * granularity.
> + *
> * For a PCIe Endpoint, PTM is only useful if the endpoint can
> * issue PTM requests to upstream devices that have PTM enabled.
> *
> @@ -179,19 +179,39 @@ int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
> * device, so there must be some implementation-specific way to
> * associate the endpoint with a time source.
> */
> - if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) {
> + if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT ||
> + pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM) {
> + if (pci_pcie_type(dev) == PCI_EXP_TYPE_UPSTREAM) {
> + ups = pci_upstream_bridge(dev);
> + if (!ups || !ups->ptm_enabled)
> + return -EINVAL;
> + }
> +
> + pci_read_config_dword(dev, pos + PCI_PTM_CTRL, &ctrl);
Why read PCI_PTM_CTRL state only for root and upstream ports? The same logic
will work for endpoints and RC endpoints right?
What not use dev->ptm_granularity for root ports?
> + ctrl |= PCI_PTM_CTRL_ENABLE;
> + } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_ENDPOINT) {
> + pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
> + if (!(cap & PCI_PTM_CAP_REQ))
> + return -EINVAL;
> +
> ups = pci_upstream_bridge(dev);
> if (!ups || !ups->ptm_enabled)
> return -EINVAL;
>
> dev->ptm_granularity = ups->ptm_granularity;
> + ctrl = PCI_PTM_CTRL_ENABLE;
> + ctrl |= dev->ptm_granularity << 8;
> } else if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) {
> + pci_read_config_dword(dev, pos + PCI_PTM_CAP, &cap);
> + if (!(cap & PCI_PTM_CAP_REQ))
> + return -EINVAL;
> +
> dev->ptm_granularity = 0;
> + ctrl = PCI_PTM_CTRL_ENABLE;
> + ctrl |= dev->ptm_granularity << 8;
> } else
> return -EINVAL;
>
> - ctrl = PCI_PTM_CTRL_ENABLE;
> - ctrl |= dev->ptm_granularity << 8;
> pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
> dev->ptm_enabled = 1;
>
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
