[PATCHv3 22/23] drm/bridge: tc358767: add IRQ and HPD support

[Tomi Valkeinen]

On 21/05/2019 17:18, Andrzej Hajda wrote:

>> DisplayPort spec talks about doing the display-props reading and EDID reading when
>> handling HPD.
>>
>> I think it would be best to change the code so that we read display props and EDID in HPD,
>> but so that we also can read them later (when needed, probably bridge enable and
>> get_modes) if we haven't done the reads already. I've had this in mind since I started the
>> series, but as it didn't feel like a simple change, I left it for later.
> 
> 
> My approach and experience suggest that detect, should be rather
> lightweight and should not modify state, I am not even sure if it is
> called at all on forced connector.

I just realized that this is not exactly perfect...

Link training can adjust the link speed and/or number of lanes, although 
the driver doesn't support this at the moment. The speed and number of 
lanes affect the video modes that are possible, so they affect get_modes.

So... I think the driver should set up the link fully before get_modes 
get called, instead of leaving the link setup to the point where we 
enable the bridge. Maybe... This is not exactly clear to me =).

In any case, I think that's future work. I have changed the code to read 
the display props in get_modes(), and I have another small fix too. I'll 
send v4 this week, and hopefully we can get this merged.

  Tomi

-- 
Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki