From: Chunyan Zhang <zhang.chunyan@linaro.org>
To: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Pratik Patel <pratikp@codeaurora.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
gregkh@linuxfoundation.org, stable@vger.kernel.org
Subject: Re: [PATCH] coresight: STM: Balance enable/disable
Date: Wed, 11 Jan 2017 19:41:22 +0800 [thread overview]
Message-ID: <CAG2=9p8CMZD37KPbp+LCyDeizUHaDmw0NfqQHPvzKdCR9L0XZw@mail.gmail.com> (raw)
In-Reply-To: <20170110173637.GA12100@linaro.org>
On 11 January 2017 at 01:36, Mathieu Poirier <mathieu.poirier@linaro.org> wrote:
> On Tue, Jan 10, 2017 at 11:21:55AM +0000, Suzuki K Poulose wrote:
>> The stm is automatically enabled when an application sets the policy
>> via ->link() call back by using coresight_enable(), which keeps the
>> refcount of the current users of the STM. However, the unlink() callback
>> issues stm_disable() directly, which leaves the STM turned off, without
>> the coresight layer knowing about it. This prevents any further uses
>> of the STM hardware as the coresight layer still thinks the STM is
>> turned on and doesn't issue an stm_enable(). Even manually enabling
>> the STM via sysfs can't really enable the hw.
>>
>> e.g,
>>
>> $ echo 1 > $CS_DEVS/$ETR/enable_sink
>> $ mkdir -p $CONFIG_FS/stp-policy/$source.0/stm_test/
>> $ echo 32768 65535 > $CONFIG_FS/stp-policy/$source.0/stm_test/channels
>> $ echo 64 > $CS_DEVS/$source/traceid
>> $ ./stm_app
>> Sending 64000 byte blocks of pattern 0 at 0us intervals
>> Success to map channel(32768~32783) to 0xffffa95fa000
>> Sending on channel 32768
>> $ dd if=/dev/$ETR of=~/trace.bin.1
>> 597+1 records in
>> 597+1 records out
>> 305920 bytes (306 kB) copied, 0.399952 s, 765 kB/s
>> $ ./stm_app
>> Sending 64000 byte blocks of pattern 0 at 0us intervals
>> Success to map channel(32768~32783) to 0xffff7e9e2000
>> Sending on channel 32768
>> $ dd if=/dev/$ETR of=~/trace.bin.2
>> 0+0 records in
>> 0+0 records out
>> 0 bytes (0 B) copied, 0.0232083 s, 0.0 kB/s
>>
>> Note that we don't get any data from the ETR for the second session.
>>
>> Also dmesg shows :
>>
>> [ 77.520458] coresight-tmc 20800000.etr: TMC-ETR enabled
>> [ 77.537097] coresight-replicator etr_replicator@20890000: REPLICATOR enabled
>> [ 77.558828] coresight-replicator main_replicator@208a0000: REPLICATOR enabled
>> [ 77.581068] coresight-funnel 208c0000.main_funnel: FUNNEL inport 0 enabled
>> [ 77.602217] coresight-tmc 20840000.etf: TMC-ETF enabled
>> [ 77.618422] coresight-stm 20860000.stm: STM tracing enabled
>> [ 139.554252] coresight-stm 20860000.stm: STM tracing disabled
>> # End of first tracing session
>> [ 146.351135] coresight-tmc 20800000.etr: TMC read start
>> [ 146.514486] coresight-tmc 20800000.etr: TMC read end
>> # Note that the STM is not turned on via stm_generic_link()->coresight_enable()
>> # and hence none of the components are turned on.
>> [ 152.479080] coresight-tmc 20800000.etr: TMC read start
>> [ 152.542632] coresight-tmc 20800000.etr: TMC read end
>>
>> This patch balances the unlink operation by using the coresight_disable(),
>> keeping the coresight layer in sync with the hardware state.
>>
>> Fixes: commit 237483aa5cf43 ("coresight: stm: adding driver for CoreSight STM component")
>> Cc: Pratik Patel <pratikp@codeaurora.org>
>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>> Cc: Chunyan Zhang <zhang.chunyan@linaro.org>
>> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> Cc: stable@vger.kernel.org # 4.7+
>> Reported-by: Robert Walker <robert.walker@arm.com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> ---
>> drivers/hwtracing/coresight/coresight-stm.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-stm.c b/drivers/hwtracing/coresight/coresight-stm.c
>> index 3524452..57b7330 100644
>> --- a/drivers/hwtracing/coresight/coresight-stm.c
>> +++ b/drivers/hwtracing/coresight/coresight-stm.c
>> @@ -356,7 +356,7 @@ static void stm_generic_unlink(struct stm_data *stm_data,
>> if (!drvdata || !drvdata->csdev)
>> return;
>>
>> - stm_disable(drvdata->csdev, NULL);
>> + coresight_disable(drvdata->csdev);
>
> This looks valid to me.
>
> Chunyan, any reason to use stm_disable() directly rather than calling it as part
> of the device OPS in coresight_disable()?
I don't think there's some special reason for this. I simply hadn't
noticed that these two operations didn't use two balanced functions.
Thanks,
Chunyan
>
> Thanks,
> Mathieu
>
>> }
>>
>> static phys_addr_t
>> --
>> 2.7.4
>>
next prev parent reply other threads:[~2017-01-11 11:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-10 11:21 [PATCH] coresight: STM: Balance enable/disable Suzuki K Poulose
2017-01-10 17:36 ` Mathieu Poirier
2017-01-11 11:41 ` Chunyan Zhang [this message]
2017-01-11 13:59 ` Suzuki K Poulose
2017-01-13 2:10 ` Chunyan Zhang
2017-01-13 16:48 ` Mathieu Poirier
2017-01-13 17:11 ` Suzuki K Poulose
2017-01-16 17:50 ` Mathieu Poirier
2017-01-16 18:00 Suzuki K Poulose
2017-01-19 11:40 ` Greg KH
2017-01-19 13:55 ` Suzuki K Poulose
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAG2=9p8CMZD37KPbp+LCyDeizUHaDmw0NfqQHPvzKdCR9L0XZw@mail.gmail.com' \
--to=zhang.chunyan@linaro.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mathieu.poirier@linaro.org \
--cc=pratikp@codeaurora.org \
--cc=stable@vger.kernel.org \
--cc=suzuki.poulose@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).