linux-kernel - Re: [PATCH] Tracing events with GPIOs

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Date:	Thu, 2 Jan 2014 13:43:40 +0100
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Alexandre Courbot <gnurou@...il.com>
Cc:	Jean-Jacques Hiblot <jjhiblot@...phandler.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	masami.hiramatsu.pt@...achi.com,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Tracing events with GPIOs

On Thu, Dec 19, 2013 at 7:52 AM, Alexandre Courbot <gnurou@...il.com> wrote:
> On Tue, Dec 17, 2013 at 9:22 AM, Jean-Jacques Hiblot
> <jjhiblot@...phandler.com> wrote:
>>
>> This patch implements a new tracing mechanism based on kprobes and using GPIO.
>> Debugging with GPIO is very common in the embedded world. At least for those of us
>> fortunate enough to have an oscilloscope or a logic analyzer on their bench...
>> This is especially true if the issue results of a hardware/sofware interaction.
>>
>> Typical use cases are :
>> * mixed software/hardware debugging. For example when the software detects a
>>   situation of interest (typically an error) it toggles a GPIO to trigger the
>>   oscilloscope acquisition.
>> * direct latency/duration measurements.
>>
>> examples:
>> To trig the oscilloscope whenever a mmc command error:
>>   echo "p:my_mmc_blk_error mmc_blk_cmd_error gpiopulse@13" > /sys/kernel/debug/tracing/kprobe_events
>>   echo 1 > /sys/kernel/debug/tracing/events/kprobes/my_mmc_blk_error/enable

I've never seen the whole patch.

Can you please repost this and include linux-gpio@...r.kernel.org and also
me on the To: line?

Yours,
Linus Walleij
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