[Intel-gfx] [PATCH 11/12] drm/i915: Check for invalid cloning earlier during modeset

[Chris Wilson]

On Wed, Jun 08, 2016 at 01:41:46PM +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> Move the encoder cloning check to happen earlier in the modeset. The
> main benefit will be that the debug output from a failed modeset will
> be less confusing as output_types can not indicate an invalid
> configuration during the later computation stages.
> 
> For instance, what happened to me was kms_setmode was attempting one
> of its invalid cloning checks during which it asked for DP+VGA cloning
> on HSW. In this case the DP .compute_config() was executed after
> the FDI .compute_config() leaving the DP link clock (1.62 in this case)
> in port_clock, and then later the FDI BW computation tried to use that
> as the FDI link clock (which should always be 2.7). 1.62 x 2 wasn't
> enough for the mode it was trying to use, and so it ended up rejecting
> the modeset, not because of an invalid cloning configuration, but
> because of supposedly running out of FDI bandwidth. Took me a while
> to figure out what had actually happened.

Did it reject the 1.62 link clock when you simply removed the
check_encoder_cloning()? Just checking... :)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre