linux-kernel - Time stamp value in printk records

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Message-ID: <7d1aee8505b91c460fee347ed4204b9a@codeaurora.org>
Date:   Mon, 30 Sep 2019 06:33:42 -0700
From:   Sodagudi Prasad <psodagud@...eaurora.org>
To:     pmladek@...e.com, sergey.senozhatsky@...il.com, rostedt@...dmis.org
Cc:     linux-kernel@...r.kernel.org
Subject: Time stamp value in printk records

Hi All,

 From Qualcomm side, we would like to check with upstream team about 
adding Raw time stamp value to printk records. On Qualcomm soc, there 
are various DSPs subsystems are there - for example audio, video and 
modem DSPs.
Adding raw timer value(along with sched_clock()) in the printk record 
helps in the following use cases –
1)	To find out which subsystem  crashed first  -  Whether application 
processor crashed first or DSP subsystem?
2)	If there are any system stability issues on the DSP side, what is the 
activity on the APPS processor side during that time?

Initially during the device boot up, printk shed_clock value can be 
matched with timer raw value used on the dsp subsystem, but after APPS 
processor suspends several times, we don’t have way to correlate the 
time stamp  value on the DSP and APPS processor. All timers(both apps 
processor timer and dsp timers) are derived from globally always on 
timer on Qualcomm soc, So keeping global timer raw values in printk 
records and dsp logs help to correlate the activity of all the 
processors in SoC.

It would be great if upstream team adds common solution this problem if 
all soc vendors would get benefit by adding raw timer value to  printk 
records.

-Thanks, Prasad

-- 
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Forum,
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