Re: [PATCH v7 0/8] drm: sun8i: Add DE2 HDMI video support

[Jernej Skrabec <jernej.skrabec@xxxxxxxxx>]

Hi Laurent,

Dne torek, 29. november 2016 23.56.31 UTC+1 je oseba Laurent Pinchart napisala:

Hi Jernej,

(CC'ing Kieran Bingham)

On Tuesday 29 Nov 2016 14:47:20 Jernej Skrabec wrote:
> Dne torek, 29. november 2016 22.37.03 UTC+1 je oseba Maxime Ripard napisala:
> > On Tue, Nov 29, 2016 at 11:18:35AM +0100, Jean-Francois Moine wrote:
> >> This patchset series adds HDMI video support to the Allwinner
> >> sun8i SoCs which include the display engine 2 (DE2).
> >> The driver contains the code for the A83T and H3 SoCs, and
> >> some H3 boards, but it could be used/extended for other SoCs
> >> (A64, H2, H5) and boards (Banana PIs, Orange PIs).
> >
> > Honestly, I'm getting a bit worried by the fact that you ignore
> > reviews.
> >
> > On the important reviews that you got that are to be seen as major
> >
> > issues that block the inclusion, we have:
> >   - The fact that the HDMI driver is actually just a designware IP,
> >     and while you should use the driver that already exists, you just
> >     duplicated all that code.
>
> That might be hard thing to do. A83T fits perfectly, but H3 and newer SoCs
> do not. They are using completely different HDMI phy. Decoupling controller
> and phy code means rewritting a good portion of the code, unless some tricks
> are applied, like calling phy function pointers, if they are defined.

Same HDMI TX but different HDMI TX PHY ? Kieran is working on decoupling the
PHY configuration code for a Renesas SoC, that might be of interest to you.

Exactly. I'm developing only U-Boot driver, but Jean-Francois will probably
have more interest in this.
 

> Register addresses also differ, but that can be easily solved by using
> undocumented magic value to restore them.

I love that :-)

Is it allowed to use magic number which was found in binary blob? I'm new in
all this.
 

> >   - The fact that you ignored Rob (v6) and I (v5) comment on using OF
> >     graph to model the connection between the display engine and the
> >     TCON. Something that Laurent also pointed out in this version.
> >  
> >   - The fact that you ignored that you needed an HDMI connector node
> >     as a child of the HDMI controller. This has been reported by Rob
> >     (v6) and yet again in this version by Laurent.
> >  
> >   - And finally the fact that we can't have several display engine in
> >     parallel, if needs be. This has happened in the past already on
> >     Allwinner SoCs, so it's definitely something we should consider in
> >     the DT bindings, since we can't break them.
> >
> > Until those are fixed, I cannot see how this driver can be merged,
> > unfortunately.

--
Regards,

Laurent Pinchart

Best regards,
Jernej Škrabec

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