[Intel-gfx] [PATCH 6/8] drm/i915: Don't calculate a new clock in ILK+ code if it is already set

[Maarten Lankhorst]

Op 14-03-16 om 14:01 schreef Ander Conselvan De Oliveira:
> On Mon, 2016-03-14 at 12:51 +0100, Maarten Lankhorst wrote:
>> Op 14-03-16 om 09:55 schreef Ander Conselvan de Oliveira:
>>> Remove the clock calculation from ironlake_crtc_compute_clock() when the
>>> encoder compute_config() already set one. The value was just thrown away
>>> in that case.
>>>
>>> Signed-off-by: Ander Conselvan de Oliveira <
>>> ander.conselvan.de.oliveira at intel.com>
>>>
>> It was thrown away, but it could still reject based on the limits, which this
>> patch changes.
>> This might be made more clear in the commit message.
> Good point. To be honest, I didn't very this as carefully as I should have
> before sending and missed that detail. It turns out that change is safe. To
> verify I extracted the relevant code and run it with all possible port clocks we
> could have with either the sdvo or the dp encoder setting the clock. See the
> attached C file. I was too lazy to actually understand what the
> g4x_find_best_dpll() does.
>
I'm not sure this would have mattered even if the limits were different, since they wouldn't be used. Just something to make a note of.

~Maarten