Re: [PATCH 1/3] drm/i915: Dont enable hpd for eDP

[Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>]

On 8/10/2015 5:44 PM, Jani Nikula wrote:
> On Mon, 10 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani@intel.com> wrote:
>> On 8/10/2015 5:07 PM, Jani Nikula wrote:
>>> On Mon, 10 Aug 2015, Sivakumar Thulasimani <sivakumar.thulasimani@intel.com> wrote:
>>>> Reviewed-by: Sivakumar Thulasimani <sivakumar.thulasimani@intel.com>
>>>>
>>>> On 8/10/2015 10:35 AM, Sonika Jindal wrote:
>>>>> With HPD support added for all ports including PORT_A, setting hpd_pin will
>>>>> result in enabling of hpd to edp as well. There is no need to enable HPD on
>>>>> PORT_A hence this patch removes hpd_pin update for PORT_A, where edp will
>>>>> be connected. it can be added back when required
>>> What? You can't just go ahead and remove HPD from eDP sinks.
>>>
>>> BR,
>>> Jani.
>> Nope, we are not removing HPD for edp sinks, it was never there in the
>> first place. It was
>> enabled for CHV (even there by mistake since PORT B/C was both DP and
>> eDP) but it was
>> never there for any other plaforms nor is it used for any purpose (PSR
>> must use it, but i
>> dont see code for it as well).
> Are you saying there's no HPD enabled in our *hardware* for eDP? Or
> driver?
>
> My point is, is this patch making it harder to enable eDP hpd handling
> (e.g. for PSR or DP link re-training) in the future? We currently take
> it into account in a few places, and if we start removing that, it will
> be a loss of effort to first remove and then add it back.
>
> BR,
> Jani.
i was referring to our driver only.

Our VLV/CHV code already receives hpd for every pps on and off which is
later ignored. if we dont disable HPD on eDPs this behavior will be extended
for all platforms which i feel is too costly to keep enabled when there 
is no
purpose for it right now.

if anyone later requires HPD , they might need it for PSR panels only and
since that code is not available as of now, this can be added along with 
those
changes so i feel this is the better tradeoff :)
>
>
>>>>> Signed-off-by: Sonika Jindal <sonika.jindal@intel.com>
>>>>> ---
>>>>>     drivers/gpu/drm/i915/intel_dp.c |    2 +-
>>>>>     1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>>>>> index fcc64e5..5a614c9 100644
>>>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>>>> @@ -5784,7 +5784,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>>>>>     	/* Set up the hotplug pin. */
>>>>>     	switch (port) {
>>>>>     	case PORT_A:
>>>>> -		intel_encoder->hpd_pin = HPD_PORT_A;
>>>>> +		/* Not enabling edp interrupts */
>>>>>     		break;
>>>>>     	case PORT_B:
>>>>>     		intel_encoder->hpd_pin = HPD_PORT_B;
>>>> -- 
>>>> regards,
>>>> Sivakumar
>>>>
>>>> _______________________________________________
>>>> Intel-gfx mailing list
>>>> Intel-gfx@lists.freedesktop.org
>>>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>> -- 
>> regards,
>> Sivakumar
>>

-- 
regards,
Sivakumar

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