Re: [PATCH 0/5] Add power feature debugfs disabling

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Jan 31, 2014 at 03:42:47PM -0600, jeff.mcgee@intel.com wrote:
> From: Jeff McGee <jeff.mcgee@intel.com>
> 
> This series has recently been accepted into the Haswell Android kernel and
> helps with debugging and profiling these power features. I would like it
> to be considered for upstream incorporation. The patches here have been
> rebased (minimal changes required) and compile-tested only.
> 
> Broad device support is provided, accept for RPS and RC6 with Broadwell
> and Valleyview. Both of these were somewhat of a moving target and I
> didn't have devices to work with. Support can of course be added with
> help from appropriate folks.
> 
> The hooks introduce some amount of overhead as an additional check is
> often needed to determine whether the feature is on or off - similar to
> the module parameters that already exist. I felt that the overhead was
> minimal enough and didn't want to ugly up the code with CONFIG_DEBUG_FS
> compile conditionals. But I'm open to the list's thoughts on this.
> 
> IGT tests of these new interfaces can certainly be added. I wanted to
> make sure there was sufficient interest in having these interfaces before
> starting on the tests. So please provide feedback.

debugfs doesn't have any abi guarantees and hence requirements are much
lower. Generally I only want a testcase for new debugfs if it is complex
infrastructure and other testcases rely on its functionality, like the CRC
stuff. Simple on/off knobs imo don't need testcases really.

Still even debugfs code has a bit of cost, so I'll hold off until someone
says that "yep, this is useful for developing stuff, I'll review it" or
some i-g-ts show up.

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch