On Mon, 28 Nov 2016 17:59:00 +0800
Icenowy Zheng <[email protected]> wrote:
> As there's currently a fork of U-Boot which provides simplefb support
> for H3, a simplefb node can be added to the device tree.
>
> Signed-off-by: Icenowy Zheng <[email protected]>
> ---
>
> I'm still not sure which pipeline should I use.
>
> And, it seems that HDMI Slow Clock is not needed?
>
> (seems that it's only for EDID, but simplefb won't use EDID)
So, I don't see how this may work.
How can the u-boot know the resolutions of the HDMI display device?
In other words: I have a new H3 board with the last u-boot and kernel.
I plug my (rather old or brand new) HDMI display device.
After powering on the system, I hope to get something on the screen.
How?
--
Ken ar c'henta? | ** Breizh ha Linux atav! **
Jef | http://moinejf.free.fr/
On Mon, Nov 28, 2016 at 11:42:18AM +0100, Jean-Francois Moine wrote:
> On Mon, 28 Nov 2016 17:59:00 +0800
> Icenowy Zheng <[email protected]> wrote:
>
> > As there's currently a fork of U-Boot which provides simplefb support
> > for H3, a simplefb node can be added to the device tree.
> >
> > Signed-off-by: Icenowy Zheng <[email protected]>
> > ---
> >
> > I'm still not sure which pipeline should I use.
> >
> > And, it seems that HDMI Slow Clock is not needed?
> >
> > (seems that it's only for EDID, but simplefb won't use EDID)
>
> So, I don't see how this may work.
> How can the u-boot know the resolutions of the HDMI display device?
>
> In other words: I have a new H3 board with the last u-boot and kernel.
> I plug my (rather old or brand new) HDMI display device.
> After powering on the system, I hope to get something on the screen.
> How?
If it works like the driver for the first display engine in U-Boot, it
will use the preferred mode reported by the EDID, and will fallback to
1024x768 if it cannot access it.
Maybe it would be worth exchanging on the EDID code that has been done
for the u-boot driver too, so that it can be fixed in your driver.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
On Tue, 29 Nov 2016 22:59:32 +0100
Maxime Ripard <[email protected]> wrote:
> > > I'm still not sure which pipeline should I use.
> > >
> > > And, it seems that HDMI Slow Clock is not needed?
> > >
> > > (seems that it's only for EDID, but simplefb won't use EDID)
> >
> > So, I don't see how this may work.
> > How can the u-boot know the resolutions of the HDMI display device?
> >
> > In other words: I have a new H3 board with the last u-boot and kernel.
> > I plug my (rather old or brand new) HDMI display device.
> > After powering on the system, I hope to get something on the screen.
> > How?
>
> If it works like the driver for the first display engine in U-Boot, it
> will use the preferred mode reported by the EDID, and will fallback to
> 1024x768 if it cannot access it.
Icenowy wrote: "simplefb won't use EDID"
Then, if it is like in the kernel, the 1024x768 mode is VGA. It does
not work with HDMI (different timings).
> Maybe it would be worth exchanging on the EDID code that has been done
> for the u-boot driver too, so that it can be fixed in your driver.
The u-boot got my code, and, up to now, I could not fix the random or
permanent failures of EDID reading in some boards.
--
Ken ar c'henta? | ** Breizh ha Linux atav! **
Jef | http://moinejf.free.fr/