[Intel-gfx] [PATCH 2/5] drm/i915: Change intel_fdi_link_freq() to 10kHz

[Daniel Vetter]

On Wed, Mar 5, 2014 at 4:04 PM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Sat, Mar 01, 2014 at 07:34:12AM +0000, Chris Wilson wrote:
>> On Fri, Feb 28, 2014 at 07:28:41PM -0300, Paulo Zanoni wrote:
>> > 2014-02-27 9:23 GMT-03:00  <ville.syrjala at linux.intel.com>:
>> > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> > >
>> > > We normally use 10Khz units when describing DP link frequency.
>> > > Have intel_fdi_link_freq() return the same units. I always get confused
>> > > when the units start to be totally different.
>> > >
>> > > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
>> >
>> > A nice simplification!
>>
>> An oversimplification. link_bw != link_freq.
>
> Yeah, I think we need a s/link_freq/link_bw now ...

To clarify: In dp we have piles of different ways to call essentially
the same thing:
- link bw code from dpcd
- symbol rate encoded at 8b/10b
- link clock

All have different units and denominators, and historically we've had
countless bugs in here. So if you want to do this please crawl through
the entire dp/fdi code and make sure to update comments and that
everything is still mostly consistent. Otherwise we don't really have
progress in this area.

I hope this helps to clarify my concern and what I guess is Chris' concern.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch