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@xxxxxxxxxxxxxxxx> 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. -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
