[Intel-gfx] [PATCH 2/2] drm/i915/vbt: split out defaults that are set when there is no VBT

[Manasi Navare]

On Mon, Mar 13, 2017 at 11:55:31AM +0200, Jani Nikula wrote:
> On Sat, 11 Mar 2017, Manasi Navare <manasi.d.navare at intel.com> wrote:
> > On Fri, Mar 10, 2017 at 03:27:58PM +0200, Jani Nikula wrote:
> >> The main thing are the DDI ports. If there's a VBT that says there are
> >> no outputs, we should trust that, and not have semi-random
> >> defaults. Unfortunately, the defaults have resulted in some Chromebooks
> >> without VBT to rely on this behaviour, so we split out the defaults for
> >> the missing VBT case.
> >> 
> >> Cc: Manasi Navare <manasi.d.navare at intel.com>
> >> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/intel_bios.c | 17 ++++++++++++++++-
> >>  1 file changed, 16 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> >> index 710988d72253..639d45c1dd2e 100644
> >> --- a/drivers/gpu/drm/i915/intel_bios.c
> >> +++ b/drivers/gpu/drm/i915/intel_bios.c
> >> @@ -1341,6 +1341,7 @@ parse_device_mapping(struct drm_i915_private *dev_priv,
> >>  	return;
> >>  }
> >>  
> >> +/* Common defaults which may be overridden by VBT. */
> >>  static void
> >>  init_vbt_defaults(struct drm_i915_private *dev_priv)
> >>  {
> >> @@ -1377,6 +1378,18 @@ init_vbt_defaults(struct drm_i915_private *dev_priv)
> >>  			&dev_priv->vbt.ddi_port_info[port];
> >>  
> >>  		info->hdmi_level_shift = HDMI_LEVEL_SHIFT_UNKNOWN;
> >> +	}
> >> +}
> >> +
> >> +/* Defaults to initialize only if there is no VBT. */
> >> +static void
> >> +init_vbt_missing_defaults(struct drm_i915_private *dev_priv)
> >> +{
> >> +	enum port port;
> >> +
> >> +	for (port = PORT_A; port < I915_MAX_PORTS; port++) {
> >> +		struct ddi_vbt_port_info *info =
> >> +			&dev_priv->vbt.ddi_port_info[port];
> >>  
> >>  		info->supports_dvi = (port != PORT_A && port != PORT_E);
> >>  		info->supports_hdmi = info->supports_dvi;
> >> @@ -1516,8 +1529,10 @@ void intel_bios_init(struct drm_i915_private *dev_priv)
> >>  	parse_ddi_ports(dev_priv, bdb);
> >>  
> >>  out:
> >> -	if (!vbt)
> >> +	if (!vbt) {
> >>  		DRM_INFO("Failed to find VBIOS tables (VBT)\n");
> >> +		init_vbt_missing_defaults(dev_priv);
> >> +	}
> >
> > So in case there is no VBT, this will set supports_DP flag on Port A.
> > What is there is no VBT and there is no eDP on Port A?
> > In this case it will still try to link train on Port A and fail..?
> > I am not sure if this case exists, but just a thought looking at it.
> 
> It's possible the case exists, but the point is that the behaviour for
> the no-VBT case remains the same before and after this patch.
> 
> BR,
> Jani.
> 
>

Ok agreed. In that case Reviewed-by: Manasi Navare <manasi.d.navare at intel.com>

Regards
Manasi

 
> > If such a case does not exist, then this will solve our problem of
> > current failures because leaving defaults on Port A. So in that case
> > it lgtm.
> >
> > Regards
> > Manasi
> >
> >
> >>  
> >>  	if (bios)
> >>  		pci_unmap_rom(pdev, bios);
> >> -- 
> >> 2.1.4
> >> 
> 
> -- 
> Jani Nikula, Intel Open Source Technology Center