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

Daniel Vetter
2015-08-25T12:57:49Z

On Mon, Aug 17, 2015 at 03:03:10PM +0300, Ville Syrjälä wrote:
> 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.

Luckily seris is in 4.4 only. Should I just drop it, or is it easily
salvageable?
-Daniel

>
> >
> >
> > > 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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--
Daniel Vetter
Software Engineer, Intel Corporation