Messages in this thread | | | Subject | Re: [PATCHv8 2/5] arm64: dts: qcom: msm8998: Add Coresight support | From | Suzuki K Poulose <> | Date | Thu, 18 Jul 2019 10:37:19 +0100 |
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On 18/07/2019 10:14, Sai Prakash Ranjan wrote: > Hi Suzuki, > > On 7/18/2019 1:58 PM, Suzuki K Poulose wrote: >> Hi Sai, >> >> >> etr@6048000 { >>> + compatible = "arm,coresight-tmc", "arm,primecell"; >>> + reg = <0x06048000 0x1000>; >>> + >>> + clocks = <&rpmcc RPM_SMD_QDSS_CLK>, <&rpmcc >>> RPM_SMD_QDSS_A_CLK>; >>> + clock-names = "apb_pclk", "atclk"; >>> + arm,scatter-gather; >> >> Please could you confirm that you have tested the scatter-gather mode >> with ETR ? Either via perf/sysfs. Please could you share your results ? >> Unless verified >> this is going to be fatal for the system. >> >> Similarly for other platforms. >> > > Yes I have tested with scatter-gather mode with ETR on all platforms > which I have posted via sysfs(not perf) before on previous versions of > this patch series and no issues were found. And I suppose this was > discussed in v2 of this patch series [1].
Using the sysfs doesn't guarantee that the ETR actually uses SG mode, unless the buffer size selected is > 1M, which is why I am more interested in the perf usage. Alternatively you may configure a larger buffer size (say, 8MB) via:
echo 0x800000 > /sys/bus/coresight/.../tmc_etr0/buffer_size
> > As said in one of the series initially [1], QCOM msm downstream kernels > have been using scatter gather mode and we haven't seen any fatal issues. > > [1] https://patchwork.kernel.org/patch/10769535/
I haven't seen any test results there either.
Cheers Suzuki
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