Re: [PATCH v3 0/3] Send a hotplug when edid changes

["Lisovskiy, Stanislav" <stanislav.lisovskiy@intel.com>]

On Tue, 2019-08-06 at 15:51 +0200, Daniel Vetter wrote:
> On Tue, Aug 06, 2019 at 03:55:48PM +0300, Stanislav Lisovskiy wrote:
> > This series introduce to drm a way to determine if something else
> > except connection_status had changed during probing, which
> > can be used by other drivers as well. Another i915 specific part
> > uses this approach to determine if edid had changed without
> > changing the connection status and send a hotplug event.
> 
> Did you read through the entire huge thread on all this (with I think
> Paul, Pekka, Ram and some others)? I feel like this is mostly taking
> that
> idea, but not taking a lot of the details we've discussed there.
> Specifically I'm not sure how userspace should handle this without
> also
> exposing the epoch counter, or at least generating a hotplug event
> for the
> specific connector. All that and more we discussed there.
> 
> And then there's the follow-up question: What's the userspace for
> this?
> Existing expectations are a minefield here, so even if you don't plan
> to
> change userspace we need to know what this is aimed for, and see
> above I
> don't think this is possible to use without userspace changes ...

Yes, sure I agree about userspace. However I guess we must start from
something at least.
I think I have seen some discussion regarding exposing this epoch
counter as a property. Was even implementing this at some point but
didn't dare to send to mailing list :)

My idea was just to expose this epoch counter as a drm property, to let
userspace then to figure out, what has happened, as imho adding
different events for this and that is a bit of an overkill and brings
additional complexity..

However, please let me know, what do you think we should do for
userspace.


-Stanislav


> -Daniel
> 
> > 
> > Stanislav Lisovskiy (3):
> >   drm: Add helper to compare edids.
> >   drm: Introduce change counter to drm_connector
> >   drm/i915: Send hotplug event if edid had changed.
> > 
> >  drivers/gpu/drm/drm_connector.c              |  1 +
> >  drivers/gpu/drm/drm_edid.c                   | 33
> > ++++++++++++++++++++
> >  drivers/gpu/drm/drm_probe_helper.c           | 29 +++++++++++++++-
> > -
> >  drivers/gpu/drm/i915/display/intel_dp.c      | 16 +++++++++-
> >  drivers/gpu/drm/i915/display/intel_hdmi.c    | 16 ++++++++--
> >  drivers/gpu/drm/i915/display/intel_hotplug.c | 21 ++++++++++---
> >  include/drm/drm_connector.h                  |  3 ++
> >  include/drm/drm_edid.h                       |  9 ++++++
> >  8 files changed, 117 insertions(+), 11 deletions(-)
> > 
> > -- 
> > 2.17.1
> > 
> 
> 
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