On 2023/10/10 15:35, Yicong Yang wrote: > On 2023/10/9 21:08, Shuai Xue wrote: >> >> >> On 2023/8/4 11:09, Shuai Xue wrote: >>> >>> >>> On 2023/8/4 10:28, Yicong Yang wrote: >>>> On 2023/8/4 9:39, Shuai Xue wrote: >>>>> >>>>> >>>>> On 2023/8/1 19:46, Yicong Yang wrote: >>>>>> On 2023/7/28 20:41, Shuai Xue wrote: >>>>>>> >>>>>>> >>>>>>> On 2023/7/27 17:39, Jonathan Cameron wrote: >>>>>>>> On Tue, 6 Jun 2023 23:14:07 +0800 >>>>>>>> Yicong Yang <yangyicong@xxxxxxxxxx> wrote: >>>>>>>> >>>>>>>>> On 2023/6/6 15:49, Shuai Xue wrote: >>>>>>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support >>>>>>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express >>>>>>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe >>>>>>>>>> Root Complex integrated End Point(RCiEP) device but only register counters >>>>>>>>>> provided by each PCIe Root Port. >>>>>>>>>> >>>>>>>>>> To facilitate collection of statistics the controller provides the >>>>>>>>>> following two features for each Root Port: >>>>>>>>>> >>>>>>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each >>>>>>>>>> low-power LTSSM state) >>>>>>>>>> - Event counters (Error and Non-Error for lanes) >>>>>>>>>> >>>>>>>>>> Note, only one counter for each type and does not overflow interrupt. >>>>>>>>>> >>>>>>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is >>>>>>>>>> named based the BDF of Root Port. For example, >>>>>>>>>> >>>>>>>>>> 30:03.0 PCI bridge: Device 1ded:8000 (rev 01) >>>>>>>>>> >>>>>>>>>> the PMU device name for this Root Port is dwc_rootport_3018. >>>>>>>>>> >>>>>>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes):: >>>>>>>>>> >>>>>>>>>> $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/ >>>>>>>>>> >>>>>>>>>> average RX bandwidth can be calculated like this: >>>>>>>>>> >>>>>>>>>> PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window >>>>>>>>>> >>>>>>>>>> Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx> >>>>>>>>>> Reported-by: kernel test robot <lkp@xxxxxxxxx> >>>>>>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@xxxxxxxxx/ >>>>>>>>>> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx> >>>>>>>> >>>>>>>> I'll review on top to avoid any duplication with Yicong. >>>>>>> >>>>>>> Thank you! It also served as a reminder that I missed Yicong's email. It appears >>>>>>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me >>>>>>> overlooking it. >>>>>>> >>>>>>>> >>>>>>>> Note I've cropped the stuff neither of us commented on so it's >>>>>>>> easier to spot the feedback. >>>>>>> >>>>>>> Thank you for noting that. My feedback is replied inline. >>>>>>> >>>>>>>> >>>>>>>> Jonathan >>>>>>>> >>>>>>>>>> --- >>>>>>>>>> drivers/perf/Kconfig | 7 + >>>>>>>>>> drivers/perf/Makefile | 1 + >>>>>>>>>> drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++ >>>>>>>>>> 3 files changed, 714 insertions(+) >>>>>>>>>> create mode 100644 drivers/perf/dwc_pcie_pmu.c >>>>>>>>>> >>>>>>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig >>>>>>>>>> index 711f82400086..6ff3921d7a62 100644 >>>>>>>>>> --- a/drivers/perf/Kconfig >>>>>>>>>> +++ b/drivers/perf/Kconfig >>>>>>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU >>>>>>>>>> Enable perf support for Marvell DDR Performance monitoring >>>>>>>>>> event on CN10K platform. >>>>>>>>>> >>>>>>>>>> +config DWC_PCIE_PMU >>>>>>>>>> + tristate "Enable Synopsys DesignWare PCIe PMU Support" >>>>>>>>>> + depends on (ARM64 && PCI) >>>>>>>>>> + help >>>>>>>>>> + Enable perf support for Synopsys DesignWare PCIe PMU Performance >>>>>>>>>> + monitoring event on Yitian 710 platform. >>>>>>>> >>>>>>>> The documentation kind of implies this isn't platform specific. >>>>>>>> If some parts are (such as which events exist) then you may want to push >>>>>>>> that to userspace / perftool with appropriate matching against specific SoC. >>>>>>>> >>>>>>>> If it is generic, then change this text to "event on platform including the Yitian 710." >>>>>>> >>>>>>> It is generic without any platform specific, so I will change it as you expected. >>>>>>> >>>>>>>> >>>>>>>>>> + >>>>>>>>>> source "drivers/perf/arm_cspmu/Kconfig" >>>>>>>>>> >>>>>>>>>> source "drivers/perf/amlogic/Kconfig" >>>>>>>> >>>>>>>>>> new file mode 100644 >>>>>>>>>> index 000000000000..8bfcf6e0662d >>>>>>>>>> --- /dev/null >>>>>>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c >>>>>>>>>> @@ -0,0 +1,706 @@ >>>>>>>> >>>>>>>> ... >>>>>>>> >>>>>>>>>> + >>>>>>>>>> +struct dwc_pcie_pmu { >>>>>>>>>> + struct pci_dev *pdev; /* Root Port device */ >>>>>>>>> >>>>>>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL >>>>>>>>> pointer. I didn't see you hold the root port to avoid the removal. >>>>>>> >>>>>>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating >>>>>>> pcie_pmu? >>>>>>> >>>>>>> pcie_pmu->pdev = pci_dev_get(); >>>>>> >>>>>> It could be one option, but will block the removal of device from userspace. Another option >>>>>> is to register a PCI bus notifier then on removal/added the driver can get notified and handle >>>>>> it, for example, remove the related PMU on the removal of the root ports. >>>>> >>>>> I see, but can root port be removed from userspace? I check the hotplug slot interface, no root >>>>> port is available to power off. >>>>> >>>> >>>> For hotplug maybe not, but user can remove certian device through sysfs: >>>> >>>> echo 1 > /sys/bus/pci/devices/<root port>/remove >>>> >>> >>> Thank you, I will add a notifier for removal/added action. >>> >>> Best Regards, >>> Shuai >> >> Hi, Yicong, >> >> I am confused when adding a notifier by bus_register_notifier(). If I have added a action to >> pdev->dev to unregister pmu: >> >> ret = perf_pmu_register(&pcie_pmu->pmu, name, -1); >> if (ret) { >> pci_err(pcie_pmu->pdev, >> "Error %d registering PMU @%x\n", ret, bdf); >> goto out; >> } >> ret = devm_add_action_or_reset( >> &pdev->dev, dwc_pcie_pmu_unregister_pmu, &pcie_pmu->pmu); >> >> the pmu will be unregister when the port removes, so accessing the NULL pointer will never happen, >> right? Do we still need the bus_register_notifier()? >> > > Not necessary, a notifier is used to notice the device removal and avoid dereferencing the > NULL pointer. If you find another way like above to avoid the issue it will be ok. Since > your pmu is 1:1 related to the root port, add a devm action to unregister the PMU on root > port removal looks better. > > Thanks. Hi, Yicong, Got it. Thank you for your quick feedback:) Best Regards. Shuai
