Re: [PATCHv2 2/4] arm64: dts: qcom: msm8996: Add Coresight support

[Suzuki K Poulose]

Sai,

On 18/01/2019 08:25, Sai Prakash Ranjan wrote:
> From: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
>
> Enable coresight support by adding device nodes for the
> available source, sinks and channel blocks on msm8996.
>
> This also adds coresight cpu debug nodes.
>
> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx>
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
> ---
>   arch/arm64/boot/dts/qcom/msm8996.dtsi | 447 ++++++++++++++++++++++++++
>   1 file changed, 447 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/msm8996.dtsi b/arch/arm64/boot/dts/qcom/msm8996.dtsi
> index 99b7495455a6..96a16d5a258c 100644
> --- a/arch/arm64/boot/dts/qcom/msm8996.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8996.dtsi

> +
> +		etr@3028000 {
> +			compatible = "arm,coresight-tmc", "arm,primecell";
> +			reg = <0x3028000 0x1000>;
> +
> +			clocks = <&rpmcc RPM_QDSS_CLK>, <&rpmcc RPM_QDSS_A_CLK>;
> +			clock-names = "apb_pclk", "atclk";

If you want to use the scatter-gather mode, you must add "arm,scatter-gather"
property to the node here.

Have you tested the scatter-gather mode on the chip ? Does that work at all ?
Note: You could try this by setting a buffer_size > 1M for the ETR and use
it as a sink from the sysfs mode.

Cheers
Suzuki