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Subject: Re: [PATCH v7 0/7] Add support for HiSilicon PCIe Tune and Trace
 device
To:     Bjorn Helgaas <helgaas@kernel.org>
References: <20220407125841.3678-1-yangyicong@hisilicon.com>
From:   Yicong Yang <yangyicong@huawei.com>
Message-ID: <701892ee-de70-e15c-6d9e-083268e94b77@huawei.com>
Date:   Thu, 14 Apr 2022 21:20:29 +0800
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Hi Bjorn,

Since it's a device about tuning and analyzing PCIe link in your realm and you've given
helpful comments in RFC and v1 version, looking forward to see your opnion on this
driver as the user interface has changed to perf. Also to confirm that the hotplug problem
mentioned in RFC[1] has been resolved in a proper way.

[1] https://lore.kernel.org/linux-pci/20200710230913.GA90375@bjorn-Precision-5520/
Thanks.

On 2022/4/7 20:58, Yicong Yang wrote:
> HiSilicon PCIe tune and trace device (PTT) is a PCIe Root Complex
> integrated Endpoint (RCiEP) device, providing the capability
> to dynamically monitor and tune the PCIe traffic (tune),
> and trace the TLP headers (trace).
> 
> PTT tune is designed for monitoring and adjusting PCIe link parameters.
> We provide several parameters of the PCIe link. Through the driver,
> user can adjust the value of certain parameter to affect the PCIe link
> for the purpose of enhancing the performance in certian situation.
> 
> PTT trace is designed for dumping the TLP headers to the memory, which
> can be used to analyze the transactions and usage condition of the PCIe
> Link. Users can choose filters to trace headers, by either requester
> ID, or those downstream of a set of Root Ports on the same core of the
> PTT device. It's also supported to trace the headers of certain type and
> of certain direction.
> 
> The driver registers a PMU device for each PTT device. The trace can
> be used through `perf record` and the traced headers can be decoded
> by `perf report`. The perf command support for the device is also
> added in this patchset. The tune can be used through the sysfs
> attributes of related PMU device. See the documentation for the
> detailed usage.
> 
> Change since v6:
> - Fix W=1 errors reported by lkp test, thanks
> 
> Change since v5:
> - Squash the PMU patch into PATCH 2 suggested by John
> - refine the commit message of PATCH 1 and some comments
> Link: https://lore.kernel.org/lkml/20220308084930.5142-1-yangyicong@hisilicon.com/
> 
> Change since v4:
> Address the comments from Jonathan, John and Ma Ca, thanks.
> - Use devm* also for allocating the DMA buffers
> - Remove the IRQ handler stub in Patch 2
> - Make functions waiting for hardware state return boolean
> - Manual remove the PMU device as it should be removed first
> - Modifier the orders in probe and removal to make them matched well
> - Make available {directions,type,format} array const and non-global
> - Using the right filter list in filters show and well protect the
>   list with mutex
> - Record the trace status with a boolean @started rather than enum
> - Optimize the process of finding the PTT devices of the perf-tool
> Link: https://lore.kernel.org/linux-pci/20220221084307.33712-1-yangyicong@hisilicon.com/
> 
> Change since v3:
> Address the comments from Jonathan and John, thanks.
> - drop members in the common struct which can be get on the fly
> - reduce buffer struct and organize the buffers with array instead of list
> - reduce the DMA reset wait time to avoid long time busy loop
> - split the available_filters sysfs attribute into two files, for root port
>   and requester respectively. Update the documentation accordingly
> - make IOMMU mapping check earlier in probe to avoid race condition. Also
>   make IOMMU quirk patch prior to driver in the series
> - Cleanups and typos fixes from John and Jonathan
> Link: https://lore.kernel.org/linux-pci/20220124131118.17887-1-yangyicong@hisilicon.com/
> 
> Change since v2:
> - address the comments from Mathieu, thanks.
>   - rename the directory to ptt to match the function of the device
>   - spinoff the declarations to a separate header
>   - split the trace function to several patches
>   - some other comments.
> - make default smmu domain type of PTT device to identity
>   Drop the RMR as it's not recommended and use an iommu_def_domain_type
>   quirk to passthrough the device DMA as suggested by Robin. 
> Link: https://lore.kernel.org/linux-pci/20211116090625.53702-1-yangyicong@hisilicon.com/
> 
> Change since v1:
> - switch the user interface of trace to perf from debugfs
> - switch the user interface of tune to sysfs from debugfs
> - add perf tool support to start trace and decode the trace data
> - address the comments of documentation from Bjorn
> - add RMR[1] support of the device as trace works in RMR mode or
>   direct DMA mode. RMR support is achieved by common APIs rather
>   than the APIs implemented in [1].
> Link: https://lore.kernel.org/lkml/1618654631-42454-1-git-send-email-yangyicong@hisilicon.com/
> [1] https://lore.kernel.org/linux-acpi/20210805080724.480-1-shameerali.kolothum.thodi@huawei.com/
> 
> Qi Liu (1):
>   perf tool: Add support for HiSilicon PCIe Tune and Trace device driver
> 
> Yicong Yang (6):
>   iommu/arm-smmu-v3: Make default domain type of HiSilicon PTT device to
>     identity
>   hwtracing: Add trace function support for HiSilicon PCIe Tune and
>     Trace device
>   hisi_ptt: Add support for dynamically updating the filter list
>   hisi_ptt: Add tune function support for HiSilicon PCIe Tune and Trace
>     device
>   docs: Add HiSilicon PTT device driver documentation
>   MAINTAINERS: Add maintainer for HiSilicon PTT driver
> 
>  Documentation/trace/hisi-ptt.rst              |  303 +++++
>  MAINTAINERS                                   |    7 +
>  drivers/Makefile                              |    1 +
>  drivers/hwtracing/Kconfig                     |    2 +
>  drivers/hwtracing/ptt/Kconfig                 |   12 +
>  drivers/hwtracing/ptt/Makefile                |    2 +
>  drivers/hwtracing/ptt/hisi_ptt.c              | 1161 +++++++++++++++++
>  drivers/hwtracing/ptt/hisi_ptt.h              |  220 ++++
>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |   16 +
>  tools/perf/arch/arm/util/auxtrace.c           |   76 +-
>  tools/perf/arch/arm/util/pmu.c                |    3 +
>  tools/perf/arch/arm64/util/Build              |    2 +-
>  tools/perf/arch/arm64/util/hisi_ptt.c         |  195 +++
>  tools/perf/util/Build                         |    2 +
>  tools/perf/util/auxtrace.c                    |    4 +
>  tools/perf/util/auxtrace.h                    |    1 +
>  tools/perf/util/hisi-ptt-decoder/Build        |    1 +
>  .../hisi-ptt-decoder/hisi-ptt-pkt-decoder.c   |  170 +++
>  .../hisi-ptt-decoder/hisi-ptt-pkt-decoder.h   |   28 +
>  tools/perf/util/hisi_ptt.c                    |  218 ++++
>  tools/perf/util/hisi_ptt.h                    |   28 +
>  21 files changed, 2448 insertions(+), 4 deletions(-)
>  create mode 100644 Documentation/trace/hisi-ptt.rst
>  create mode 100644 drivers/hwtracing/ptt/Kconfig
>  create mode 100644 drivers/hwtracing/ptt/Makefile
>  create mode 100644 drivers/hwtracing/ptt/hisi_ptt.c
>  create mode 100644 drivers/hwtracing/ptt/hisi_ptt.h
>  create mode 100644 tools/perf/arch/arm64/util/hisi_ptt.c
>  create mode 100644 tools/perf/util/hisi-ptt-decoder/Build
>  create mode 100644 tools/perf/util/hisi-ptt-decoder/hisi-ptt-pkt-decoder.c
>  create mode 100644 tools/perf/util/hisi-ptt-decoder/hisi-ptt-pkt-decoder.h
>  create mode 100644 tools/perf/util/hisi_ptt.c
>  create mode 100644 tools/perf/util/hisi_ptt.h
>