Re: [PATCH v2 0/3] Add support for RAS DES feature in PCIe DW controller

From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Shradha Todi <shradha.t@samsung.com>
Cc: lpieralisi@kernel.org, kw@linux.com, robh@kernel.org,
	bhelgaas@google.com, jingoohan1@gmail.com,
	gustavo.pimentel@synopsys.com, josh@joshtriplett.org,
	lukas.bulwahn@gmail.com, hongxing.zhu@nxp.com,
	pankaj.dubey@samsung.com, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org
Subject: Re: [PATCH v2 0/3] Add support for RAS DES feature in PCIe DW controller
Date: Thu, 30 Nov 2023 22:25:14 +0530	[thread overview]
Message-ID: <20231130165514.GW3043@thinkpad> (raw)
In-Reply-To: <20231130115044.53512-1-shradha.t@samsung.com>

On Thu, Nov 30, 2023 at 05:20:41PM +0530, Shradha Todi wrote:
> DesignWare controller provides a vendor specific extended capability
> called RASDES as an IP feature. This extended capability  provides
> hardware information like:
>  - Debug registers to know the state of the link or controller. 
>  - Error injection mechanisms to inject various PCIe errors including
>    sequence number, CRC
>  - Statistical counters to know how many times a particular event
>    occurred
> 
> However, in Linux we do not have any generic or custom support to be
> able to use this feature in an efficient manner. This is the reason we
> are proposing this framework. Debug and bring up time of high-speed IPs
> are highly dependent on costlier hardware analyzers and this solution
> will in some ways help to reduce the HW analyzer usage.
> 
> The debugfs entries can be used to get information about underlying
> hardware and can be shared with user space. Separate debugfs entries has
> been created to cater to all the DES hooks provided by the controller.
> The debugfs entries interacts with the RASDES registers in the required
> sequence and provides the meaningful data to the user. This eases the
> effort to understand and use the register information for debugging.
> 
> v1 version was posted long back and for some reasons I couldn't work on
> it. I apologize for the long break. I'm restarting this activity and
> have taken care of all previous review comments shared.
> v1: https://lore.kernel.org/all/20210518174618.42089-1-shradha.t@samsung.com/T/
> 

There is already a series floating to add similar functionality via perf
subsystem: https://lore.kernel.org/linux-pci/20231121013400.18367-1-xueshuai@linux.alibaba.com/

- Mani

> Shradha Todi (3):
>   PCI: dwc: Add support for vendor specific capability search
>   PCI: debugfs: Add support for RASDES framework in DWC
>   PCI: dwc: Create debugfs files in DWC driver
> 
>  drivers/pci/controller/dwc/Kconfig            |   8 +
>  drivers/pci/controller/dwc/Makefile           |   1 +
>  .../controller/dwc/pcie-designware-debugfs.c  | 476 ++++++++++++++++++
>  .../controller/dwc/pcie-designware-debugfs.h  |   0
>  drivers/pci/controller/dwc/pcie-designware.c  |  20 +
>  drivers/pci/controller/dwc/pcie-designware.h  |  18 +
>  6 files changed, 523 insertions(+)
>  create mode 100644 drivers/pci/controller/dwc/pcie-designware-debugfs.c
>  create mode 100644 drivers/pci/controller/dwc/pcie-designware-debugfs.h
> 
> -- 
> 2.17.1
> 

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