Date:   Mon, 25 Jul 2022 08:32:47 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Yicong Yang <yangyccccc@...il.com>
Cc:     alexander.shishkin@...ux.intel.com, gregkh@...uxfoundation.org,
        leo.yan@...aro.org, james.clark@....com, will@...nel.org,
        robin.murphy@....com, acme@...nel.org, peterz@...radead.org,
        corbet@....net, mark.rutland@....com, jonathan.cameron@...wei.com,
        john.garry@...wei.com, helgaas@...nel.org,
        lorenzo.pieralisi@....com, suzuki.poulose@....com, joro@...tes.org,
        shameerali.kolothum.thodi@...wei.com, mingo@...hat.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-pci@...r.kernel.org, linux-perf-users@...r.kernel.org,
        iommu@...ts.linux-foundation.org, iommu@...ts.linux.dev,
        linux-doc@...r.kernel.org, prime.zeng@...wei.com,
        liuqi115@...wei.com, zhangshaokun@...ilicon.com,
        linuxarm@...wei.com, yangyicong@...ilicon.com, bagasdotme@...il.com
Subject: Re: [PATCH v11 0/8] Add support for HiSilicon PCIe Tune and Trace device

On Fri, 22 Jul 2022 at 08:53, Yicong Yang <yangyccccc@...il.com> wrote:
>
> 在 7/21/2022 11:43 PM, Mathieu Poirier 写道:
> > On Thu, 21 Jul 2022 at 07:03, <yangyicong@...wei.com> wrote:
> >> From: Yicong Yang <yangyicong@...ilicon.com>
> >>
> >> 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 v10:
> >> - Use title case in the documentation
> >> - Add RB from Bagas, thanks.
> >> Link: https://lore.kernel.org/lkml/20220714092710.53486-1-yangyicong@hisilicon.com/
> >>
> >> Change since v9:
> >> - Add sysfs ABI description documentation
> >> - Remove the controversial available_{root_port, requester}_filters sysfs file
> >> - Shorten 2 tune sysfs attributes name and add some comments
> >> - Move hisi_ptt_process_auxtrace_info() to Patch 6.
> >> - Add RB from Leo and Ack-by from Mathieu, thanks!
> > You can add my Ack-by to patch 03 as well.  See below for another comment.
>
> Thanks!
>
> >> Link: https://lore.kernel.org/lkml/20220606115555.41103-1-yangyicong@hisilicon.com/
> >>
> >> Change since v8:
> >> - Cleanups and one minor fix from Jonathan and John, thanks
> >> Link: https://lore.kernel.org/lkml/20220516125223.32012-1-yangyicong@hisilicon.com/
> >>
> >> Change since v7:
> >> - Configure the DMA in probe rather than in runtime. Also use devres to manage
> >>   PMU device as we have no order problem now
> >> - Refactor the config validation function per John and Leo
> >> - Use a spinlock hisi_ptt::pmu_lock instead of mutex to serialize the perf process
> >>   in pmu::start as it's in atomic context
> >> - Only commit the traced data when stop, per Leo and James
> >> - Drop the filter dynamically updating patch from this series to simply the review
> >>   of the driver. That patch will be send separately.
> >> - add a cpumask sysfs attribute and handle the cpu hotplug events, follow the
> >>   uncore PMU convention
> >> - Other cleanups and fixes, both in driver and perf tool
> >> Link: https://lore.kernel.org/lkml/20220407125841.3678-1-yangyicong@hisilicon.com/
> >>
> >> 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 (3):
> >>   perf tool: arm: Refactor event list iteration in
> >>     auxtrace_record__init()
> >>   perf tool: Add support for HiSilicon PCIe Tune and Trace device driver
> >>   perf tool: Add support for parsing HiSilicon PCIe Trace packet
> >>
> >> Yicong Yang (5):
> >>   iommu/arm-smmu-v3: Make default domain type of HiSilicon PTT device to
> >>     identity
> >>   hwtracing: hisi_ptt: Add trace function support for HiSilicon PCIe
> >>     Tune and Trace device
> >>   hwtracing: hisi_ptt: Add tune function support for HiSilicon PCIe Tune
> >>     and Trace device
> >>   docs: trace: Add HiSilicon PTT device driver documentation
> >>   MAINTAINERS: Add maintainer for HiSilicon PTT driver
> >>
> >>  .../ABI/testing/sysfs-devices-hisi_ptt        |   61 +
> >>  Documentation/trace/hisi-ptt.rst              |  298 +++++
> >>  Documentation/trace/index.rst                 |    1 +
> >>  MAINTAINERS                                   |    8 +
> >>  drivers/Makefile                              |    1 +
> >>  drivers/hwtracing/Kconfig                     |    2 +
> >>  drivers/hwtracing/ptt/Kconfig                 |   12 +
> >>  drivers/hwtracing/ptt/Makefile                |    2 +
> >>  drivers/hwtracing/ptt/hisi_ptt.c              | 1032 +++++++++++++++++
> >>  drivers/hwtracing/ptt/hisi_ptt.h              |  200 ++++
> >>  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |   21 +
> > Everything above needs to go in one patchset and everything below in
> > another one.  The first patchset will need to be merged before the
> > second one.  Someone already commented on that.
>
> ok. I put them together to provide an overall view of this and thought maintainers can take
> them separately. Will spilt the driver part and perf tool patches.
>
> I still don't know who will finally take the driver part. It should be Alexander from maintainer
> list but I got no response yet for a long time. Any hint for this?

It will either be Peter, Greg or myself.  We'll see when we get there.

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