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From: Suzuki K Poulose <suzuki.poulose@arm.com>
To: saiprakash.ranjan@codeaurora.org, gregkh@linuxfoundation.org,
	mathieu.poirier@linaro.org, leo.yan@linaro.org,
	alexander.shishkin@linux.intel.com, mike.leach@linaro.org,
	robh+dt@kernel.org, bjorn.andersson@linaro.org,
	devicetree@vger.kernel.org, david.brown@linaro.org,
	mark.rutland@arm.com
Cc: rnayak@codeaurora.org, marc.w.gonzalez@free.fr,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
	sibis@codeaurora.org, vivek.gautam@codeaurora.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv8 2/5] arm64: dts: qcom: msm8998: Add Coresight support
Date: Thu, 18 Jul 2019 10:37:19 +0100
Message-ID: <281e3548-af53-f9a7-b9e4-813b448ab078@arm.com> (raw)
In-Reply-To: <4854b0f7-6a81-bc87-3e63-d2b7c68a44f6@codeaurora.org>



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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Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-12 14:16 [PATCHv8 0/5] Add coresight support for SDM845, MSM8998 and MSM8996 Sai Prakash Ranjan
2019-07-12 14:16 ` [PATCHv8 1/5] arm64: dts: qcom: sdm845: Add Coresight support Sai Prakash Ranjan
2019-07-12 16:44   ` Suzuki K Poulose
2019-07-12 16:49     ` saiprakash.ranjan
2019-07-19  9:46   ` Suzuki K Poulose
2019-07-19 10:28     ` Sai Prakash Ranjan
2019-07-12 14:16 ` [PATCHv8 2/5] arm64: dts: qcom: msm8998: " Sai Prakash Ranjan
2019-07-18  8:28   ` Suzuki K Poulose
2019-07-18  9:14     ` Sai Prakash Ranjan
2019-07-18  9:37       ` Suzuki K Poulose [this message]
2019-07-18  9:53         ` Sai Prakash Ranjan
2019-07-12 14:16 ` [PATCHv8 3/5] arm64: dts: qcom: msm8996: " Sai Prakash Ranjan
2019-07-17 17:00   ` Mathieu Poirier
2019-07-18  5:47     ` Sai Prakash Ranjan
2019-07-18 15:31       ` Mathieu Poirier
2019-07-18 15:48         ` Bjorn Andersson
2019-07-12 14:16 ` [PATCHv8 4/5] coresight: etm4x: Add ETM PIDs for SDM845 and MSM8996 Sai Prakash Ranjan
2019-07-17 17:40   ` Mathieu Poirier
2019-07-12 14:16 ` [PATCHv8 5/5] coresight: cpu-debug: Add support for Qualcomm Kryo Sai Prakash Ranjan
2019-07-17 16:56   ` Mathieu Poirier
2019-07-21 14:35     ` Leo Yan
2019-07-22  5:48       ` Sai Prakash Ranjan

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