From: Suzuki.Poulose@arm•com (Suzuki K Poulose)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH V3 13/18] coresight: tmc: make sysFS and Perf mode mutually exclusive
Date: Mon, 25 Apr 2016 16:11:26 +0100 [thread overview]
Message-ID: <571E339E.9080306@arm.com> (raw)
In-Reply-To: <CANLsYkxJB2HzsDqwdKBJmUfVgnH7q7dF6+GQFhuSF+6-LzB_9Q@mail.gmail.com>
On 25/04/16 16:05, Mathieu Poirier wrote:
> On 25 April 2016 at 08:52, Suzuki K Poulose <Suzuki.Poulose@arm•com> wrote:
>> On 25/04/16 15:48, Mathieu Poirier wrote:
>>>
>>> On 25 April 2016 at 08:32, Suzuki K Poulose <Suzuki.Poulose@arm•com>
>>> wrote:
>>>>
>>>> On 22/04/16 18:14, Mathieu Poirier wrote:
>>
>>
>>>>> + spin_lock_irqsave(&drvdata->spinlock, flags);
>>>>> + if (drvdata->reading) {
>>>>> + ret = -EINVAL;
>>>>> + goto out;
>>>>> + }
>>>>> +
>>>>> + val = local_xchg(&drvdata->mode, mode);
>>>>> + /*
>>>>> + * In Perf mode there can be only one writer per sink. There
>>>>> + * is also no need to continue if the ETR is already operated
>>>>> + * from sysFS.
>>>>> + */
>>>>> + if (val != CS_MODE_DISABLED) {
>>>>
>>>>
>>>>
>>>> Could val be CS_MODE_PERF ? In other words, should we be checking :
>>>> if (val == CS_MODE_SYSFS) instead ?
>>>
>>>
>>> If we check for CS_MODE_SYSFS we also have to check for CS_MODE_PERF,
>>> which is two checks rather than a single one with the current
>>> solution.
>>
>>
>> I am confused now. The comment says, we want to check for sysfs mode and
>> don't continue in that case. So, we shouldn't be worried about PERF mode.
>
> You are correct about the sysFS part, but the first sentence of the
> comment also mention that in perf mode there can only be one writer
> per sink. Otherwise ring buffers for one session would end up with
> traces from other ongoing sessions, and that is not taking into
> account the buffer management nightmares it would cause.
OK, in either case, val == CS_MODE_SYSFS is much better check there, to
what we want to do
Suzuki
next prev parent reply other threads:[~2016-04-25 15:11 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-22 17:13 [PATCH V3 00/18] coresight: tmc: make driver usable by Perf Mathieu Poirier
2016-04-22 17:13 ` [PATCH V3 01/18] coresight: tmc: modifying naming convention Mathieu Poirier
2016-04-22 17:13 ` [PATCH V3 02/18] coresight: tmc: waiting for TMCReady bit before programming Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 03/18] coresight: tmc: re-implementing tmc_read_prepare/unprepare() functions Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 04/18] coresight: tmc: clearly define number of transfers per burst Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 05/18] coresight: tmc: introducing new header file Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 06/18] coresight: tmc: cleaning up " Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 07/18] coresight: tmc: splitting driver in ETB/ETF and ETR components Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 08/18] coresight: tmc: making prepare/unprepare functions generic Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 09/18] coresight: tmc: allocating memory when needed Mathieu Poirier
2016-04-25 10:20 ` Suzuki K Poulose
2016-04-25 14:24 ` Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 10/18] coresight: tmc: getting the right read_count on tmc_open() Mathieu Poirier
2016-04-25 10:47 ` Suzuki K Poulose
2016-04-25 14:25 ` Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 11/18] coresight: tmc: adding mode of operation for link/sinks Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 12/18] coresight: tmc: dump system memory content only when needed Mathieu Poirier
2016-04-25 11:16 ` Suzuki K Poulose
2016-04-25 14:38 ` Mathieu Poirier
2016-04-25 14:49 ` Suzuki K Poulose
2016-04-22 17:14 ` [PATCH V3 13/18] coresight: tmc: make sysFS and Perf mode mutually exclusive Mathieu Poirier
2016-04-25 14:32 ` Suzuki K Poulose
2016-04-25 14:48 ` Mathieu Poirier
2016-04-25 14:52 ` Suzuki K Poulose
2016-04-25 15:05 ` Mathieu Poirier
2016-04-25 15:11 ` Suzuki K Poulose [this message]
2016-04-25 15:18 ` Mathieu Poirier
2016-04-26 9:23 ` Suzuki K Poulose
2016-04-22 17:14 ` [PATCH V3 14/18] coresight: tmc: keep track of memory width Mathieu Poirier
2016-04-25 14:41 ` Suzuki K Poulose
2016-04-25 14:55 ` Mathieu Poirier
2016-04-25 15:09 ` Suzuki K Poulose
2016-04-25 15:25 ` Mathieu Poirier
2016-04-25 15:28 ` Suzuki K Poulose
2016-04-22 17:14 ` [PATCH V3 15/18] coresight: moving struct cs_buffers to header file Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 16/18] coresight: tmc: implementing TMC-ETF AUX space API Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 17/18] coresight: tmc: implementing TMC-ETR " Mathieu Poirier
2016-04-22 17:14 ` [PATCH V3 18/18] coresight: configuring ETF in FIFO mode when acting as link Mathieu Poirier
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