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.
