Re: [PATCH] drm/i915/vbt: Assume port A is connected to eDP when there's no VBT

[Jani Nikula <jani.nikula@intel.com>]

On Thu, 10 Aug 2017, rodrigo.vivi@gmail.com wrote:
>> On Aug 9, 2017, at 8:20 PM, Dhinakaran Pandiyan <dhnkrn@gmail.com> wrote:
>> 
>> We currently assume port A is connected to a DP sink when VBT is absent,
>> instead assume it is connected to an eDP sink, which seems like a more
>> common configuration. Although I don't have data to back this up,
>> it is still just as valid as asumming port A is not eDP.
>
> I also don't have enough data, but it is the most common configuration on the rvp boards that I see around...
> Also the missing vbt case is more for dev platforms anyways right?!

I presume certain chromebooks. Maybe. I really wish we'd never added
this kind of "helpful" defaults, because turns out we may end up getting
stuck with them [1]. Please refrain from applying this patch until that
bug is resolved; we may need to revert.

BR,
Jani.


[1] https://bugs.freedesktop.org/show_bug.cgi?id=101745



>
>
>> This reverts to
>> the behavior before a98d9c1 ("drm/i915/ddi: Rely on VBT DDI port info for
>> eDP detection") except only when there is no VBT. Knowing whether a panel
>> is eDP or not from the panel itself would have been nicer, but I cannot
>> find any DPCD registers that provide this reliably.
>> 
>> Cc: Jani Nikula <jani.nikula@intel.com>
>> Cc: Imre Deak <imre.deak@intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
>> Cc: Clint Taylor <clinton.a.taylor@intel.com>
>
> +Joe
> Does this fix the issue Joe has on his GLK B0?
>
>> 
>> Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
>> ---
>> drivers/gpu/drm/i915/intel_bios.c | 1 +
>> 1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
>> index 82b144c..89a405e 100644
>> --- a/drivers/gpu/drm/i915/intel_bios.c
>> +++ b/drivers/gpu/drm/i915/intel_bios.c
>> @@ -1403,6 +1403,7 @@ init_vbt_missing_defaults(struct drm_i915_private *dev_priv)
>>        info->supports_dvi = (port != PORT_A && port != PORT_E);
>>        info->supports_hdmi = info->supports_dvi;
>>        info->supports_dp = (port != PORT_E);
>> +        info->supports_edp = (port == PORT_A);
>
>>    }
>> }
>> 
>> -- 
>> 2.7.4
>> 
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-- 
Jani Nikula, Intel Open Source Technology Center
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