[PATCH weston v6 49/73] compositor-drm: move connector fields into drm_head

Pekka Paalanen ppaalanen at gmail.com
Wed Apr 18 08:53:38 UTC 2018

On Thu, 12 Apr 2018 14:58:13 +0200
Daniel Stone <daniel at fooishbar.org> wrote:

> Hi Pekka,
> On 12 April 2018 at 14:53, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > On Thu, 12 Apr 2018 15:37:43 +0300 Pekka Paalanen <ppaalanen at gmail.com> wrote:  
> >> On Thu, 12 Apr 2018 14:03:32 +0200 Daniel Stone <daniel at fooishbar.org> wrote:  
> >> > One thing I'm missing (possibly post-lunch tiredness, but): when
> >> > exactly would we replace a connector? Is it only if we have a
> >> > hot-unplugged connector which later appears as a connector of the same
> >> > name? e.g. DP-4 as MST disappears, and then reappears with the same
> >> > name but a different connector ID.  
> >>
> >> Every time there is any hotplug event, all connectors' information is
> >> reloaded. The information could have changed without us seeing the
> >> connector disconnected in between. This runs by connector IDs, not
> >> names.  
> >  
> >> drm_head is always created for all connectors we find, regardless of
> >> connected or not.  
> >
> > Oops, I suppose this happens at a later step in the series. I think my
> > explanation should still apply even at this step though, for the missed
> > unplug event part.  
> Cool, that's what I was hoping the answer was. It does make sense
> later on in the series; it was just at this point that I was worried I
> was missing something. I don't think there's much point in reshuffling
> it, but maybe a very small comment in the commit message would be
> useful.


I have added this to the commit message:

"While incurring the churn to move several fields into struct drm_head, 
also refactor out drm_head_assign_connector_info(). This function is 
needed later when drm_heads will exist regardless of connected status, 
as every hotplug event will need to update the state of all connectors.
At that point we will also start handling connector changes that do not
go through an intermediate disconnected state. This refactoring is trivial 
enough to be in this patch to reduce the total amount of changes to be 

Hopefully that covers it.

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