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SubjectRe: [PATCH 1/2] PCI/DPC: Add 'nodpc' parameter
On 2018-08-16 02:56, Jon Derrick wrote:
> Some users may want to disable downstream port containment (DPC), so
> give them this option
>
> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> ---
> drivers/pci/pci.c | 2 ++
> drivers/pci/pci.h | 6 ++++++
> drivers/pci/pcie/dpc.c | 48
> ++++++++++++++++++++++++++++++++++++++----------
> include/linux/pci.h | 6 ++++++
> 4 files changed, 52 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 80da484..4e629c2 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -6062,6 +6062,8 @@ static int __init pci_setup(char *str)
> pcie_ats_disabled = true;
> } else if (!strcmp(str, "noaer")) {
> pci_no_aer();
> + } else if (!strcmp(str, "nodpc")) {
> + pci_no_dpc();
> } else if (!strcmp(str, "earlydump")) {
> pci_early_dump = true;
> } else if (!strncmp(str, "realloc=", 8)) {
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 6e0d152..f73f29e 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -536,4 +536,10 @@ static inline void
> pci_aer_clear_fatal_status(struct pci_dev *dev) { }
> static inline void pci_aer_clear_device_status(struct pci_dev *dev) {
> }
> #endif
>
> +#ifdef CONFIG_PCIE_DPC
> +void pci_no_dpc(void);
> +#else
> +static inline void pci_no_dpc(void) { }
> +#endif
> +
> #endif /* DRIVERS_PCI_H */
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index f03279f..068fca0 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -44,6 +44,18 @@ struct dpc_dev {
> "Memory Request Completion Timeout", /* Bit Position 18 */
> };
>
> +static int pcie_dpc_disable;
> +
> +void pci_no_dpc(void)
> +{
> + pcie_dpc_disable = 1;
> +}
> +
> +bool pci_dpc_available(void)
> +{
> + return !pcie_dpc_disable && pci_aer_available() && pci_msi_enabled();

1) why do you check pci_aer_available() ?
2) and pci_aer_available() already internally checks pci_msi_enabled();

> +}
> +
> static int dpc_wait_rp_inactive(struct dpc_dev *dpc)
> {
> unsigned long timeout = jiffies + HZ;
> @@ -209,6 +221,17 @@ static irqreturn_t dpc_irq(int irq, void *context)
> return IRQ_HANDLED;
> }
>
> +static void dpc_disable(struct pci_dev *pdev)
> +{
> + u16 cap_pos, ctl;
> +
> + cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
> + pci_read_config_word(pdev, cap_pos + PCI_EXP_DPC_CTL, &ctl);
> + ctl &= ~(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_EN_NONFATAL |
> + PCI_EXP_DPC_CTL_INT_EN);
> + pci_write_config_word(pdev, cap_pos + PCI_EXP_DPC_CTL, ctl);
> +}
> +
> #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
> static int dpc_probe(struct pcie_device *dev)
> {
> @@ -221,9 +244,16 @@ static int dpc_probe(struct pcie_device *dev)
> if (pcie_aer_get_firmware_first(pdev))
> return -ENOTSUPP;
>
> + if (!pci_dpc_available()) {
> + status = -ENOTSUPP;
> + goto disable_dpc;
> + }
> +
> dpc = devm_kzalloc(device, sizeof(*dpc), GFP_KERNEL);
> - if (!dpc)
> - return -ENOMEM;
> + if (!dpc) {
> + status = -ENOMEM;
> + goto disable_dpc;
> + }
>
> dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
> dpc->dev = dev;
> @@ -235,7 +265,7 @@ static int dpc_probe(struct pcie_device *dev)
> if (status) {
> dev_warn(device, "request IRQ%d failed: %d\n", dev->irq,
> status);
> - return status;
> + goto disable_dpc;
> }
>
> pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
> @@ -260,17 +290,15 @@ static int dpc_probe(struct pcie_device *dev)
> FLAG(cap, PCI_EXP_DPC_CAP_SW_TRIGGER), dpc->rp_log_size,
> FLAG(cap, PCI_EXP_DPC_CAP_DL_ACTIVE));
> return status;
> +
> +disable_dpc:
> + dpc_disable(pdev);
> + return status;
> }
>
> static void dpc_remove(struct pcie_device *dev)
> {
> - struct dpc_dev *dpc = get_service_data(dev);
> - struct pci_dev *pdev = dev->port;
> - u16 ctl;
> -
> - pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
> - ctl &= ~(PCI_EXP_DPC_CTL_EN_FATAL | PCI_EXP_DPC_CTL_INT_EN);
> - pci_write_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, ctl);
> + dpc_disable(dev->port);
> }
>
> static struct pcie_port_service_driver dpcdriver = {
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 5454e6b..559b792 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1473,6 +1473,12 @@ static inline int pci_irqd_intx_xlate(struct
> irq_domain *d,
> static inline bool pci_aer_available(void) { return false; }
> #endif
>
> +#ifdef CONFIG_PCIE_DPC
> +bool pci_dpc_available(void);
> +#else
> +static inline bool pci_dpc_available(void) { return false; }
> +#endif
> +
> #ifdef CONFIG_PCIE_ECRC
> void pcie_set_ecrc_checking(struct pci_dev *dev);
> void pcie_ecrc_get_policy(char *str);

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