On Sat, 11 Mar 2017, Manasi Navare <manasi.d.navare@xxxxxxxxx> 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@xxxxxxxxx>
>> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
>> ---
>> 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.
> 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
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