Re: [PATCH] [media] hdmi: added functions for MPEG InfoFrames

[Enric Balletbo Serra <eballetbo@gmail.com>]

Hello Thierry,

2015-11-19 13:29 GMT+01:00 Enric Balletbo Serra <eballetbo@gmail.com>:
> Hello Thierry,
>
> 2015-11-19 12:51 GMT+01:00 Thierry Reding <treding@nvidia.com>:
>> On Tue, Nov 17, 2015 at 11:55:53PM +0100, Enric Balletbo Serra wrote:
>>> Hello Thierry,
>>>
>>> 2015-11-17 13:55 GMT+01:00 Thierry Reding <treding@nvidia.com>:
>>> > On Mon, Nov 16, 2015 at 05:28:24PM +0100, Enric Balletbo Serra wrote:
>>> >> Hello Thierry,
>>> >>
>>> >> Many thanks for your comments.
>>> >>
>>> >> 2015-11-16 12:50 GMT+01:00 Thierry Reding <treding@nvidia.com>:
>>> >> > On Sat, Nov 14, 2015 at 07:38:19PM +0100, Enric Balletbo i Serra wrote:
>>> >> >> The MPEG Source (MS) InfoFrame is in EIA/CEA-861B. It describes aspects of
>>> >> >> the compressed video stream that were used to produce the uncompressed
>>> >> >> video.
>>> >> >>
>>> >> >> The patch adds functions to work with MPEG InfoFrames.
>>> >> >>
>>> >> >> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
>>> >> >> ---
>>> >> >>  drivers/video/hdmi.c | 156 +++++++++++++++++++++++++++++++++++++++++++++++++++
>>> >> >>  include/linux/hdmi.h |  24 ++++++++
>>> >> >>  2 files changed, 180 insertions(+)
>>> >> >
>>> >> > According to the CEA specification a source is expected to send this
>>> >> > type of infoframe once per video frame. I'm curious how you envision
>>> >> > this to be ensured. Would hardware provide a mechanism to store this
>>> >> > data and send the infoframe automatically? How would you ensure that
>>> >> > updates sent to the hardware match the upcoming frame?
>>> >> >
>>> >>
>>> >> To be honest I'm not sure if I have the full picture. In the use case
>>> >> I'm trying there is a hardware mechanism to store the data and send
>>> >> the infoframe through a "Packet Send Control Register".
>>> >
>>> > Okay, sounds like the hardware will automatically send out packets at
>>> > the right time. That still leaves open the issue of how to ensure this
>>> > is synchronized with userspace. Perhaps this could be done by attaching
>>> > a property to a framebuffer, so that we'd know what exact frame the meta
>>> > data is attached to and when to update the FIFOs for the infoframe.
>>> >
>>> > Usually it's a good idea to send this type of patch as part of a larger
>>> > series precisely so that people can see how it is used. That should make
>>> > it easier to see if this is good enough or needs some more thought on
>>> > how to synchronize. Do you have any code that you could post that makes
>>> > use of this new infoframe?
>>> >
>>>
>>> I was thinking use this and other helpers in the anx7814 bridge
>>> driver[1], I thought that this patch should go through another tree,
>>> this is the reason why I send it separately, but If you want or you
>>> prefer I can send as part of these patch series.
>>>
>>> [1] https://lkml.org/lkml/2015/11/13/284
>>
>> I haven't seen those patches yet. I should've been Cc'ed on those
>> patches since I'm technically the maintainer of drm/bridge. Did the
>> get_maintainer.pl script not list me?
>>
>
> Mmm, just checked and yes, get_maintainer list you, so probably I did
> something getting the maintainers.
> Sorry.
>
>> In my opinion, it's usually a good idea to keep all dependencies in a
>> single series, just so people get a better picture of what you're
>> submitting. Of course that's just my opinion, somebody else may yell at
>> you because they get Cc'ed on patches that they're not interested in...
>>
>> As for merging patches, it's usually best to let maintainers figure that
>> out once the series is in good shape.
>>
>> Thierry


As you suggested I included this patch series with anx7814 bridge
driver series. So you can see the context. Please feel free to comment
anything.

https://lkml.org/lkml/2015/12/4/66

Regards,

Enric