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

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

On Tue, Jun 04, 2019 at 12:44:48PM -0700, Manasi Navare wrote:
> 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?

I was thinking just moving it to the start of intel_dp_init_connector(),
but I suppose moving it even earlier would be possible since intel_ddi.c
doesn't seem to do any of the eDP->HDMI fallback we needed to add for
VLV/CHV.

> 
> 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
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel
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