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Date: Thu, 16 Aug 2018 15:45:07 +0000
From: "Derrick, Jonathan" <jonathan.derrick@...el.com>
To: "poza@...eaurora.org" <poza@...eaurora.org>
CC: "liudongdong3@...wei.com" <liudongdong3@...wei.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
"Busch, Keith" <keith.busch@...el.com>,
"okaya@...nel.org" <okaya@...nel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"helgaas@...nel.org" <helgaas@...nel.org>
Subject: Re: [PATCH 1/2] PCI/DPC: Add 'nodpc' parameter
On Thu, 2018-08-16 at 14:57 +0530, poza@...eaurora.org wrote:
> 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@...el.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() ?
I'd assumed a dependency on aer, but looking at it again I see it calls
into err.c without a requirement on aer.
Then it also seems the pci_aer_available() and AER dependency check in
portdrv_core.c is unneccessary too.
> 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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