Re: [PATCH v4 4/5] arm64/perf: Enable PMCR long cycle counter bit

From: David Daney
Date: Thu Feb 18 2016 - 13:58:06 EST


On 02/18/2016 09:34 AM, Will Deacon wrote:
On Thu, Feb 18, 2016 at 05:50:13PM +0100, Jan Glauber wrote:
With the long cycle counter bit (LC) disabled the cycle counter is not
working on ThunderX SOC (ThunderX only implements Aarch64).
Also, according to documentation LC == 0 is deprecated.

To keep the code simple the patch does not introduce 64 bit wide counter
functions. Instead writing the cycle counter always sets the upper
32 bits so overflow interrupts are generated as before.

Original patch from Andrew Pinksi <Andrew.Pinksi@xxxxxxxxxxxxxxxxxx>

What does this mean? Do we need Andrew's S-o-B, or is this a fresh patch?

I don't believe we need Andrew's S-o-B as the assertion of the Developer's Certificate of Origin 1.1 clauses (a), (b) and (d) is being made. Specifically, clause (c) does not apply.

However this may be a gray area, so we could put on Andrew's S-o-B if that would make everybody happier.

David Daney



Will

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