linux-kernel - Re: [PATCH 0/4] PCI: dwc: Add PTM sysfs support

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Message-ID: <Z7Syf2LXEuKFToV4@lizhi-Precision-Tower-5810>
Date: Tue, 18 Feb 2025 11:17:03 -0500
From: Frank Li <Frank.li@....com>
To: manivannan.sadhasivam@...aro.org
Cc: Shuai Xue <xueshuai@...ux.alibaba.com>,
	Jing Zhang <renyu.zj@...ux.alibaba.com>,
	Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
	Jingoo Han <jingoohan1@...il.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>, Shradha Todi <shradha.t@...sung.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-perf-users@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 0/4] PCI: dwc: Add PTM sysfs support

On Tue, Feb 18, 2025 at 08:06:39PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> Hi,
>
> This series adds sysfs support for PCIe PTM in Synopsys Designware IPs.
>
> First patch moves the common DWC struct definitions (dwc_pcie_vsec_id) to
> include/pci/pcie-dwc.h from dwc-pcie-pmu driver. This allows reusing the same
> definitions in pcie-designware-sysfs driver introduced in this series and also
> in the debugfs series by Shradha [1].
>
> Second patch adds support for searching the Vendor Specific Extended Capability
> (VSEC) in the pcie-designware driver. This patch was originally based on
> Shradha's patch [2], but modified to accept 'struct dwc_pcie_vsec_id' to avoid
> iterating through the vsec_ids in the driver.
>
> Third patch adds the actual sysfs support for PTM in a new file
> pcie-designware-sysfs.c built along with pcie-designware.c.
>
> Finally, fourth patch masks the PTM_UPDATING interrupt in the pcie-qcom-ep
> driver to avoid processing the interrupt for each PTM context update.
>
> Testing
> =======
>
> This series is tested on Qcom SA8775p Ride Mx platform where one SA8775p acts as
> RC and another as EP with following instructions:
>
> RC
> --
>
> $ echo 1 > /sys/devices/platform/1c10000.pcie/dwc/ptm/ptm_context_valid
>
> EP
> --
>
> $ echo auto > /sys/devices/platform/1c10000.pcie-ep/dwc/ptm/ptm_context_update
>
> $ cat /sys/devices/platform/1c10000.pcie-ep/dwc/ptm/ptm_local_clock
> 159612570424
>
> $ cat /sys/devices/platform/1c10000.pcie-ep/dwc/ptm/ptm_master_clock
> 159609466232
>
> $ cat /sys/devices/platform/1c10000.pcie-ep/dwc/ptm/ptm_t1
> 159609466112
>
> $ cat /sys/devices/platform/1c10000.pcie-ep/dwc/ptm/ptm_t4
> 159609466518


I am not sure what real means by only show these number. It is quite
similar to network 1588, ptp. There were already linux-ptp
https://www.kernel.org/doc/html/v5.5/driver-api/ptp.html

Can we use similar method to sync local timer to master? I think it is real
purpuse of PTM.

Frank

>
> NOTE: To make use of the PTM feature, the host PCIe client driver has to call
> 'pci_enable_ptm()' API during probe. This series was tested with enabling PTM in
> the MHI host driver with a local change (which will be upstreamed later).
> Technically, PTM could also be enabled in the pci_endpoint_test driver, but I
> didn't add the change as I'm not sure we'd want to add random PCIe features in
> the test driver without corresponding code in pci-epf-test driver.
>
> Merging Strategy
> ================
>
> I'd like to have an ACK from the perf maintainers to take the whole series
> through PCI tree.
>
> [1] https://lore.kernel.org/linux-pci/20250214105007.97582-1-shradha.t@samsung.com
> [2] https://lore.kernel.org/linux-pci/20250214105007.97582-2-shradha.t@samsung.com
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
> Manivannan Sadhasivam (4):
>       perf/dwc_pcie: Move common DWC struct definitions to 'pcie-dwc.h'
>       PCI: dwc: Add helper to find the Vendor Specific Extended Capability (VSEC)
>       PCI: dwc: Add sysfs support for PTM
>       PCI: qcom-ep: Mask PTM_UPDATING interrupt
>
>  Documentation/ABI/testing/sysfs-platform-dwc-pcie  |  70 ++++++
>  MAINTAINERS                                        |   2 +
>  drivers/pci/controller/dwc/Makefile                |   2 +-
>  drivers/pci/controller/dwc/pcie-designware-ep.c    |   3 +
>  drivers/pci/controller/dwc/pcie-designware-host.c  |   4 +
>  drivers/pci/controller/dwc/pcie-designware-sysfs.c | 278 +++++++++++++++++++++
>  drivers/pci/controller/dwc/pcie-designware.c       |  46 ++++
>  drivers/pci/controller/dwc/pcie-designware.h       |  22 ++
>  drivers/pci/controller/dwc/pcie-qcom-ep.c          |   8 +
>  drivers/perf/dwc_pcie_pmu.c                        |  23 +-
>  include/linux/pcie-dwc.h                           |  42 ++++
>  11 files changed, 478 insertions(+), 22 deletions(-)
> ---
> base-commit: 2014c95afecee3e76ca4a56956a936e23283f05b
> change-id: 20250218-pcie-qcom-ptm-bf6952f5c4e5
>
> Best regards,
> --
> Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
>
>