Re: [PATCH] drm/bridge: dw_hdmi: add cec notifier support

From: Russell King - ARM Linux
Date: Thu Jul 06 2017 - 07:46:12 EST

On Thu, Jul 06, 2017 at 01:29:54PM +0200, Neil Armstrong wrote:
> On 07/06/2017 01:05 PM, Russell King - ARM Linux wrote:
> > On Thu, Jul 06, 2017 at 12:33:06PM +0200, Neil Armstrong wrote:
> >> From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> >>
> >> Add CEC notifier support to the HDMI bridge driver, so that the CEC
> >> part of the IP can receive its physical address.
> >>
> >> Tested-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> >> Acked-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> >> Acked-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> >> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
> >> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> >> ---
> >> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 18 ++++++++++++++++++
> >> 1 file changed, 18 insertions(+)
> >>
> >> Hi Archit, Hans,
> >>
> >> This is repost of Russell's patch from his dw-hdmi CEC patchset.
> >>
> >> Since his CEC implementation will be integrated in the bridge driver,
> >> this notifier patch won't be re-posted.
> >>
> >> But the Amlogic Platform needs a notifier since it uses a standalone CEC
> >> controller.
> >
> > Without this, the dw-hdmi CEC support will be totally useless anyway,
> > and it's pointless to merge it without this patch.
> >
> Hi Russell,
> While following discussion on your last patchset, it seems you agreed with Hans
> to no more rely on the cec-notifier but directly call the dw-hdmi-cec functions.

Incorrect. I think you're looking at the discussion in "thread mode"
and assuming that messages are stored in date order...

There was a discussion about removing the cec-notifier which happened
on June 1st/2nd, based off the covering email.

However, there was a later discussion on June 9th (sparked by your
requirement) which changed the resolution from "lets remove the
notifier" to "we need to keep the notifier". This was based on
patch 2/4.

I never posted an updated patch set, because of the dependencies, but
Hans decided on June 12th to do I-don't-know-what with the patches I
sent, resulting in what we have queued up today. This brought the
sub-thread containing the cec-notifier removal discussion to be _after_
the June 9th discussion, which is probably what's causing some
confusion here.

However, I can assure you that the resolution of the discussion with
the cec-notifier was that it should remain in place - this is from
the last few messages in the discussion:

Hans wrote on 9th June:
| You wrote on 9th June:
| > It won't since the Meson platform needs it...
| Ah, I wasn't aware of that when I wrote my original comments. In that case
| we do need the notifier. Which is fine, as long as the reason for that is
| documented.

>From what you're saying, it sounds like the CEC dw-hdmi-cec.c still
relies on the notifier, but the patch which adds the CEC notifier
to dw-hdmi.c was omited from what Hans did, which will result in the
whole thing being a total waste of time.

> Anyway, if this patch is merged separately and you still depend on it,
> you could still rebase on it when it appears on drm-misc-next...

Well, from what I can see in 4.12, the cec-notifier stuff is rather
broken (tda998x has stopped working as its stuck with a physical
address of f.f.f.f) so I think the whole thing is rather moot right
now. I don't yet know what's going on with that, other than the
notifier stuff seems to not be working, despite being enabled in
the .config.

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