Re: [PATCH 0/7] drm/i915: Move DP link parameters out from intel_dp

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Aug 17, 2015 at 10:42:23AM +0200, Maarten Lankhorst wrote:
> Hey,
> 
> Op 06-07-15 om 14:09 schreef ville.syrjala@linux.intel.com:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >
> > While working on CHV DPIO powergating I relized DP .compute_config() was
> > clobbering lane_count etc. stored in intel_dp. This could cause problems
> > if we do the .compute_config() but later fail the modeset for some reason.
> > Any subsequent link re-training might then fail if intel_dp->lane_count
> > etc. got changed.
> >
> > The reason I ran into this during the DPIO powergating work was that I may
> > need to know which lanes he active when shutting down the link. However
> > .compute_config() already clobbered that information by the time I need it.
> > By moving it to the pipe config we avoid that problem as well.
> >
> > I also cleaned up the limited color range handling a bit while I was
> > in the neighborhood.
> >
> > Ville Syrjälä (7):
> >   drm/i915: Clean up DP/HDMI limited color range handling
> >   drm/i915: Don't use link_bw for PLL setup
> ^
> >   drm/i915: Don't pass clock to DDI PLL select functions
> >   drm/i915: Avoid confusion between DP and TRANS_DP_CTL in DP
> >     .get_config()
> >   drm/i915: Move intel_dp->lane_count into pipe_config
> ^Your patch series breaks MST entirely.
> 
> drm_encoder->crtc will be NULL and dereferencing crtc->config will fail on the primary encoder:
> 
> intel_mst_pre_enable_dp(mst_enc) -> intel_ddi_init_dp_buf_reg(mst_enc->primary). -> primary->crtc = NULL, OOPS.
> 
> Voltage training was failing too and I was getting a MCE until I reverted the crtc->config changes from this series..

Hmm. Our modeset code vs. mst seems to a huge mess. To fix it properly
we should split the link compute/setup from the pipe config entirely.
As a short term solution I suppose I could pass the pipe config into
various dp link setup functions rather than assume that we can dig it
out from the encoder->crtc.

> 
> 
> >   drm/i915: Don't use link_bw to select between TP1 and TP3
> >   drm/i915: Kill intel_dp->{link_bw,rate_select}
> >
> >  drivers/gpu/drm/i915/i915_reg.h      |   3 +
> >  drivers/gpu/drm/i915/intel_ddi.c     |  41 ++++----
> >  drivers/gpu/drm/i915/intel_display.c |   7 +-
> >  drivers/gpu/drm/i915/intel_dp.c      | 177 ++++++++++++++++++++---------------
> >  drivers/gpu/drm/i915/intel_dp_mst.c  |  19 ++--
> >  drivers/gpu/drm/i915/intel_drv.h     |   9 +-
> >  drivers/gpu/drm/i915/intel_hdmi.c    |  26 +++--
> >  7 files changed, 155 insertions(+), 127 deletions(-)
> >

-- 
Ville Syrjälä
Intel OTC
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