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
