On Thu, 2017-08-17 at 12:46 -0700, Manasi Navare wrote:
> On Thu, Aug 17, 2017 at 07:01:05AM +0000, Rodrigo Vivi wrote:
> >    On Wed, Aug 16, 2017 at 11:51 PM Manasi Navare
> >    <[1]manasi.d.nav...@intel.com> wrote:
> > 
> >      In case of eDP because the panel has a fixed mode we cannot
> >      link train fallback and prune modes since this results in
> >      no modes available for eDP connector.
> > 
> >    What about downclock modes?!
> 
> What are the downclock modes? We have seen an issue with pruning modes
> in case of eDP panel where we end up pruning the mode due to link train
> fallback and then we get an error saying "No modes available for the
> connector"
> 

fwiw I've got two laptops with eDP's having more than ten modes.

> > 
> >      Also since its a panel, link training should not fail dynamically
> >      based on cable conditions like in  case of DP.
> > 
> >    Is there any bug associated with this patch?
> 
> Yes this is the bug:
> https://bugs.freedesktop.org/show_bug.cgi?id=101518
> But the reason I didnt have this in the Fixes tab is because
> this patch will not fix the bug, it will just isolate to it being
> a bug with AUX Timeouts warning.
> 
> Regards
> Manasi
> 
> > 
> >      Cc: Jani Nikula <[2]jani.nik...@linux.intel.com>
> >      Cc: Jim Bride <[3]jim.br...@linux.intel.com>
> >      Cc: Ville Syrjälä <[4]ville.syrj...@linux.intel.com>
> >      Cc: Daniel Vetter <[5]daniel.vet...@intel.com>
> >      Signed-off-by: Manasi Navare <[6]manasi.d.nav...@intel.com>
> >      ---
> >       drivers/gpu/drm/i915/intel_dp.c               | 2 +-
> >       drivers/gpu/drm/i915/intel_dp_link_training.c | 3 ++-
> >       drivers/gpu/drm/i915/intel_drv.h              | 1 +
> >       3 files changed, 4 insertions(+), 2 deletions(-)
> >      diff --git a/drivers/gpu/drm/i915/intel_dp.c
> >      b/drivers/gpu/drm/i915/intel_dp.c
> >      index 4fd4853..edac0c8 100644
> >      --- a/drivers/gpu/drm/i915/intel_dp.c
> >      +++ b/drivers/gpu/drm/i915/intel_dp.c
> >      @@ -109,7 +109,7 @@ static const int default_rates[] = { 162000,
> >      270000, 540000 };
> >        * If a CPU or PCH DP output is attached to an eDP panel, this
> >      function
> >        * will return true, and false otherwise.
> >        */
> >      -static bool is_edp(struct intel_dp *intel_dp)
> >      +bool is_edp(struct intel_dp *intel_dp)
> >       {
> >              struct intel_digital_port *intel_dig_port =
> >      dp_to_dig_port(intel_dp);
> >      diff --git a/drivers/gpu/drm/i915/intel_dp_link_training.c
> >      b/drivers/gpu/drm/i915/intel_dp_link_training.c
> >      index 05907fa..18ec61f 100644
> >      --- a/drivers/gpu/drm/i915/intel_dp_link_training.c
> >      +++ b/drivers/gpu/drm/i915/intel_dp_link_training.c
> >      @@ -332,7 +332,8 @@ intel_dp_start_link_train(struct intel_dp
> >      *intel_dp)
> >                            intel_connector->[7]base.base.id,
> >                            intel_connector->[8]base.name,
> >                            intel_dp->link_rate, intel_dp->lane_count);
> >      -       if (!intel_dp_get_link_train_fallback_values(intel_dp,
> >      +       /* Dont fallback and prune modes if its eDP */
> >      +       if (!is_edp(intel_dp) &&
> >      !intel_dp_get_link_train_fallback_values(intel_dp,
> > 
> >      intel_dp->link_rate,
> > 
> >      intel_dp->lane_count))
> >                      /* Schedule a Hotplug Uevent to userspace to start
> >      modeset */
> >      diff --git a/drivers/gpu/drm/i915/intel_drv.h
> >      b/drivers/gpu/drm/i915/intel_drv.h
> >      index fa47285..9800a15 100644
> >      --- a/drivers/gpu/drm/i915/intel_drv.h
> >      +++ b/drivers/gpu/drm/i915/intel_drv.h
> >      @@ -1548,6 +1548,7 @@ static inline unsigned int
> >      intel_dp_unused_lane_mask(int lane_count)
> >       }
> >       bool intel_dp_read_dpcd(struct intel_dp *intel_dp);
> >      +bool is_edp(struct intel_dp *intel_dp);
> >       int intel_dp_link_required(int pixel_clock, int bpp);
> >       int intel_dp_max_data_rate(int max_link_clock, int max_lanes);
> >       bool intel_digital_port_connected(struct drm_i915_private
> >      *dev_priv,
> >      --
> >      2.1.4
> >      _______________________________________________
> >      Intel-gfx mailing list
> >      [9]Intel-gfx@lists.freedesktop.org
> >      [10]https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> > 
> > References
> > 
> >    1. mailto:manasi.d.nav...@intel.com
> >    2. mailto:jani.nik...@linux.intel.com
> >    3. mailto:jim.br...@linux.intel.com
> >    4. mailto:ville.syrj...@linux.intel.com
> >    5. mailto:daniel.vet...@intel.com
> >    6. mailto:manasi.d.nav...@intel.com
> >    7. http://base.base.id/
> >    8. http://base.name/
> >    9. mailto:Intel-gfx@lists.freedesktop.org
> >   10. https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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