[PATCH v10 4/5] drivers/perf: add DesignWare PCIe PMU driver

[Ilkka Koskinen]

Hi Shuai,

On Sat, 4 Nov 2023, 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 a PCIe
> configuration space register block provided by each PCIe Root Port in a
> Vendor-Specific Extended Capability named RAS D.E.S (Debug, Error
> injection, and Statistics).
>
> To facilitate collection of statistics the controller provides the
> following two features for each Root Port:
>
> - one 64-bit counter for Time Based Analysis (RX/TX data throughput and
>  time spent in each low-power LTSSM state) and
> - one 32-bit counter for Event Counting (error and non-error events for
>  a specified lane)
>
> Note: There is no interrupt for counter overflow.
>
> 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 bytes)::
>
>    $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>
> average RX bandwidth can be calculated like this:
>
>    PCIe TX Bandwidth = Rx_PCIe_TLP_Data_Payload / Measure_Time_Window
>
> Signed-off-by: Shuai Xue <xueshuai at linux.alibaba.com>
> Reviewed-by: Baolin Wang <baolin.wang at linux.alibaba.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron at huawei.com>
> Reviewed-by: Yicong Yang <yangyicong at hisilicon.com>

Thanks for the driver! I finally found some time to test your driver on 
AmpereOne and it seemed to work fine. I had to do a couple of changes 
though such as adding Ampere vendor ID and support multiple PCIe domains. 
Given your driver is already in v10 and you have got quite a few 
reviewed and acked bys, I wonder if it's better to add my changes to 
your patches or me to create new patches on top of yours? I'm fine with 
either. Any thoughts?

Cheers, Ilkka