On Thu, Dec 19, 2013 at 7:52 AM, Alexandre Courbot [off-list ref] wrote:

On Tue, Dec 17, 2013 at 9:22 AM, Jean-Jacques Hiblot
[off-list ref] wrote:

quoted

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@vger.kernel.org and also
me on the To: line?

Yours,
Linus Walleij