[alsa-devel] [PATCH 00/13] Remove mach-kirkwood and mach-dove

[Russell King - ARM Linux]

On Mon, Jun 30, 2014 at 09:16:43AM +0200, Jean-Francois Moine wrote:
> On Sun, 29 Jun 2014 22:35:11 +0100
> Russell King - ARM Linux <linux at arm.linux.org.uk> wrote:
> 
> > There is actually a cubox regression which has yet to be tracked down.
> > Running with my kernel (which is not-DT based) runs perfectly.  With
> > DT, HDMI output can be unstable.
> 
> Russell,
> 
> What is this HDMI problem with DT?
> 
> I am running a DT based kernel on my Cubox for more than 1 year and the
> only problem I have is a random black screen at startup time, and this
> black screen problem also exists with the old non-DT kernels from
> SolidRun.

The problem is that the picture appears for about a second, then goes black
for maybe a couple of seconds, then reappears for about a second and this
cycle repeats.  Rebooting into the DT kernel doesn't fix it.  Rebooting
back into the non-DT kernel does fix it.  Then if you boot back into the DT
kernel it's back again.  Boot back into the non-DT kernel and it's again
fixed.

I have compared register settings for the Si5351, LCD controllers and the
TDA998x between the non-DT and DT versions, and can find no differences
there.  Yet, DT kernels are the only kernels which exhibit this behaviour.
Non-DT kernels (which I've run continuously including many reboots) for
the last two years have *never* shown this problem.

I have also verified that the HDMI clock is correct.  The problem occurs
at both 1080p and 720p resolutions (which are the two that are used during
boot - I have the kernel using 720p, and Xorg uses 1080p.)

I should also point out that in both cases, it is the _same_ kernel binary
(3.15) that I'm running - the DT test case just has the DT blob attached
whereas the non-DT case boots without (and therefore falls back to the
old platform stuff.)

-- 
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.