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Date: Tue, 27 Feb 2018 14:09:43 +0530
From: poza@...eaurora.org
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Philippe Ombredanne <pombredanne@...b.com>,
Thomas Gleixner <tglx@...utronix.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Kate Stewart <kstewart@...uxfoundation.org>,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
Dongdong Liu <liudongdong3@...wei.com>,
Keith Busch <keith.busch@...el.com>, Wei Zhang <wzhang@...com>,
Sinan Kaya <okaya@...eaurora.org>,
Timur Tabi <timur@...eaurora.org>
Subject: Re: [PATCH v11 6/7] PCI: Unify wait for link active into generic pci
On 2018-02-24 21:11, Bjorn Helgaas wrote:
> In subject:
>
> s/pci/PCI/
sure.
>
> On Fri, Feb 23, 2018 at 01:54:03PM +0530, Oza Pawandeep wrote:
>> Clients such as pciehp, dpc are using pcie_wait_link_active, which
>> waits
>> till the link becomes active or inactive.
>
> Use "()" after function names so we have a visual clue that they are
> functions.
>
>> Made generic function and moved it to drivers/pci/pci.c
>>
>> Signed-off-by: Oza Pawandeep <poza@...eaurora.org>
>>
>> diff --git a/drivers/pci/hotplug/pciehp_hpc.c
>> b/drivers/pci/hotplug/pciehp_hpc.c
>> index 18a42f8..de9b0ea 100644
>> --- a/drivers/pci/hotplug/pciehp_hpc.c
>> +++ b/drivers/pci/hotplug/pciehp_hpc.c
>> @@ -231,25 +231,11 @@ bool pciehp_check_link_active(struct controller
>> *ctrl)
>> return ret;
>> }
>>
>> -static void __pcie_wait_link_active(struct controller *ctrl, bool
>> active)
>> +static bool pcie_wait_link_active(struct controller *ctrl)
>> {
>> - int timeout = 1000;
>> -
>> - if (pciehp_check_link_active(ctrl) == active)
>> - return;
>> - while (timeout > 0) {
>> - msleep(10);
>> - timeout -= 10;
>> - if (pciehp_check_link_active(ctrl) == active)
>> - return;
>> - }
>> - ctrl_dbg(ctrl, "Data Link Layer Link Active not %s in 1000 msec\n",
>> - active ? "set" : "cleared");
>> -}
>> + struct pci_dev *pdev = ctrl_dev(ctrl);
>>
>> -static void pcie_wait_link_active(struct controller *ctrl)
>> -{
>> - __pcie_wait_link_active(ctrl, true);
>> + return pci_wait_for_link(pdev, true);
>> }
>>
>> static bool pci_bus_check_dev(struct pci_bus *bus, int devfn)
>> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
>> index f6a4dd1..f8d44b4 100644
>> --- a/drivers/pci/pci.c
>> +++ b/drivers/pci/pci.c
>> @@ -4176,6 +4176,37 @@ static int pci_pm_reset(struct pci_dev *dev,
>> int probe)
>> return 0;
>> }
>>
>> +/**
>> + * pci_wait_for_link - Wait for link till its active/inactive
>
> s/its/it's/
sure.
>
>> + * @pdev: Bridge device
>> + * @active: waiting for active or inactive ?
>> + *
>> + * Use this to wait till link becomes active or inactive.
>> + */
>> +bool pci_wait_for_link(struct pci_dev *pdev, bool active)
>
> I think this should be "pcie_wait_for_link()". There's no concept of a
> link in conventional PCI.
>
>> +{
>> + int timeout = 1000;
>> + bool ret;
>> + u16 lnk_status;
>> +
>> + for (;;) {
>> + pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
>> + ret = !!(lnk_status & PCI_EXP_LNKSTA_DLLLA);
>> + if (ret == active)
>> + return true;
>> + if (timeout <= 0)
>> + break;
>> + timeout -= 10;
>> + }
>> +
>> + dev_printk(KERN_DEBUG, &pdev->dev,
>
> pci_info(). Distros often seem to have logging configured so
> KERN_DEBUG things aren't captured, and this definitely seems worth
> capturing.
>
>> + "Data Link Layer Link Active not %s in 1000 msec\n",
>> + active ? "set" : "cleared");
>> +
>> + return false;
>> +}
>> +EXPORT_SYMBOL(pci_wait_for_link);
>
> I don't think this needs to be exported.
>
sure.
>> void pci_reset_secondary_bus(struct pci_dev *dev)
>> {
>> u16 ctrl;
>> diff --git a/drivers/pci/pcie/pcie-dpc.c b/drivers/pci/pcie/pcie-dpc.c
>> index 5c01c63..e15bcda 100644
>> --- a/drivers/pci/pcie/pcie-dpc.c
>> +++ b/drivers/pci/pcie/pcie-dpc.c
>> @@ -120,19 +120,9 @@ static int dpc_wait_rp_inactive(struct dpc_dev
>> *dpc)
>>
>> static void dpc_wait_link_inactive(struct dpc_dev *dpc)
>> {
>> - unsigned long timeout = jiffies + HZ;
>> struct pci_dev *pdev = dpc->dev->port;
>> - struct device *dev = &dpc->dev->device;
>> - u16 lnk_status;
>>
>> - pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
>> - while (lnk_status & PCI_EXP_LNKSTA_DLLLA &&
>> - !time_after(jiffies, timeout)) {
>> - msleep(10);
>> - pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnk_status);
>> - }
>> - if (lnk_status & PCI_EXP_LNKSTA_DLLLA)
>> - dev_warn(dev, "Link state not disabled for DPC event\n");
>> + pci_wait_for_link(pdev, false);
>> }
>>
>> /**
>> diff --git a/include/linux/pci.h b/include/linux/pci.h
>> index 024a1be..cb674c3 100644
>> --- a/include/linux/pci.h
>> +++ b/include/linux/pci.h
>> @@ -1195,6 +1195,7 @@ int pci_add_ext_cap_save_buffer(struct pci_dev
>> *dev,
>> int pci_request_selected_regions(struct pci_dev *, int, const char
>> *);
>> int pci_request_selected_regions_exclusive(struct pci_dev *, int,
>> const char *);
>> void pci_release_selected_regions(struct pci_dev *, int);
>> +bool pci_wait_for_link(struct pci_dev *pdev, bool active);
>
> I don't think this needs to be available outside the PCI core, so this
> could probably be declared in drivers/pci/pci.h
>
thanks, will move it.
>> /* drivers/pci/bus.c */
>> struct pci_bus *pci_bus_get(struct pci_bus *bus);
>> --
>> Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
>> Technologies, Inc.,
>> a Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a
>> Linux Foundation Collaborative Project.
>>
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