Re: [PATCH] drm/i915/dp: Correctly advertise HBR3 for GEN11+

[Manasi Navare <manasi.d.navare@intel.com>]

On Tue, Jun 04, 2019 at 03:51:58PM +0300, Ville Syrjälä wrote:
> On Mon, Jun 03, 2019 at 02:49:40PM -0700, matthew.s.atwood@intel.com wrote:
> > From: Matt Atwood <matthew.s.atwood@intel.com>
> > 
> > intel_dp_set_source_rates() calls intel_dp_is_edp(), which is unsafe to
> > use before encoder_type is set. This caused GEN11+ to incorrectly strip
> > HBR3 from source rates. Move intel_dp_set_source_rates() to after
> > encoder_type is set. Add comment to intel_dp_is_edp() describing unsafe
> > usages.
> > 
> > Fixes: b265a2a6255f5 ("drm/i915/icl: combo port vswing programming
> > changes per BSPEC")
> > Signed-off-by: Matt Atwood <matthew.s.atwood@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_dp.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 24b56b2a76c8..a4490bcad684 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -141,6 +141,8 @@ static const u8 valid_dsc_slicecount[] = {1, 2, 4};
> >   *
> >   * If a CPU or PCH DP output is attached to an eDP panel, this function
> >   * will return true, and false otherwise.
> > + *
> > + * This function is not safe to use prior to encoder type being set.
> >   */
> >  bool intel_dp_is_edp(struct intel_dp *intel_dp)
> >  {
> > @@ -7342,8 +7344,6 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> >  		 intel_dig_port->max_lanes, port_name(port)))
> >  		return false;
> >  
> > -	intel_dp_set_source_rates(intel_dp);
> > -
> >  	intel_dp->reset_link_params = true;
> >  	intel_dp->pps_pipe = INVALID_PIPE;
> >  	intel_dp->active_pipe = INVALID_PIPE;
> > @@ -7388,6 +7388,8 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> >  			type == DRM_MODE_CONNECTOR_eDP ? "eDP" : "DP",
> >  			port_name(port));
> >  
> > +	intel_dp_set_source_rates(intel_dp);
> > +
> 
> I would suggest moving the encoder->type setup earlier so that we might
> avoid hitting this same problem in the future.

IMHO, Ideally this encoder->type should be set in intel_ddi_init or intel_ddi_init_dp_connector()
for us to never get into a situation where intel_dp_is_edp() is called before encoder->type is set.

Is that what you are recommending?

Manasi

> 
> >  	drm_connector_init(dev, connector, &intel_dp_connector_funcs, type);
> >  	drm_connector_helper_add(connector, &intel_dp_connector_helper_funcs);
> >  
> > -- 
> > 2.17.2
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Ville Syrjälä
> Intel
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