On 08/21/2014 11:52 AM, Thierry Reding wrote: > On Thu, Aug 21, 2014 at 11:41:59AM +0200, Boris BREZILLON wrote: >> On Thu, 21 Aug 2014 11:04:07 +0200 >> Thierry Reding <thierry.reding@xxxxxxxxx> wrote: >> >>> On Thu, Aug 21, 2014 at 10:37:06AM +0200, Boris BREZILLON wrote: >>>> Hi Ludovic, >>>> >>>> On Thu, 21 Aug 2014 10:16:19 +0200 >>>> Ludovic Desroches <ludovic.desroches@xxxxxxxxx> wrote: >>>> >>>>> Hi Boris, >>>>> >>>>> You can add >>>>> >>>>> Tested-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx> >>>> >>>> Thanks for testing this driver. >>>> >>>>> >>>>> Only one issue but not related to your patches, you can't display >>>>> quickly the bootup logo since the panel detection takes too much >>>>> time. >>>> >>>> Yes, actually this is related to the device probe order: the >>>> hlcdc-display-controller device is probed before the simple-panel, thus >>>> nothing is detected on the RGB connector (I use of_drm_find_panel to >>>> check for panel availability) when the display controller is >>>> instantiated. I rely on the default polling infrastructure provided by >>>> the DRM/KMS framework which polls for a new connector every 10s, and >>>> this is far more than you kernel boot time. >>>> >>>> Do anyone see a solution to reduce this delay (without changing the >>>> polling interval). I thought we could add a notifier infrastructure to >>>> the DRM panel framework, but I'm not sure this is how you want things >>>> done... >>> >>> Other drivers return -EPROBE_DEFER when a panel hasn't been registered >>> yet. This will automatically take care of ordering things in a way that >>> DRM/KMS will only be initialized after the panel has been probed. >> >> Actually I'd like to avoid doing this with a deferred probe, because, >> AFAIU, the remote endpoint is not tightly linked with the display >> controller driver (I mean the display controller can still be >> initialized without having a display connected on it). >> Moreover the atmel dev kit I'm using has an HDMI bridge connected on >> the same RGB connector and I'd like to use it in a near future. >> Returning -EPROBE_DEFER in case of several devices connected on the >> same connector implies that I'll have to wait for all the remote >> end-points to be available before my display controller could be >> instantiated. >> >> While this could be acceptable when all drivers are statically linked >> in the kernel, it might be problematic when you're using modules, >> meaning that you won't be able to display anything on your LCD panel >> until your HDMI bridge module has been loaded. > > No. HDMI should be using proper hotplugging anyway, hence it should be > always be loaded anyway. You're in for a world of pain if you think you > can run DRM with a driver that's composed of separate kernel modules. > > Also if you don't want to use deferred probe, then you're in for the > full hotplugging panel dance and that implies that you need to fix a > bunch of things in DRM (one being the framebuffer console instantiation > that I referred to in the other thread). You also can't be using the > current device tree bindings because they all assume a dependency from > the display controller/output to the panel. For hotplugging you'd need > the dependency the other way around (the panel needs to refer to the > output by phandle). I have tested panel as a module in exynos-dsi + panel-s6e8aa0 configuration, everything works. There is a workaround for fb console not being reconfigurable, but it does not make thing worse than before. And I do not see a problem with phandles, ie in DT they point both ways, according to binding advices at the time, but in the code it is display controller/encoder which is looking for the panel. Regards Andrzej > >>> That >>> will still cause some delay before everything gets set up, but hopefully >>> less than what you're seeing now. There's also another thread where this >>> is being discussed because deferred probing is causing "unacceptable" >>> delays as well. >> >> Could you point this thread out to me please ? > > I Cc'ed you on it. > > Thierry > > > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/dri-devel > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
