> -----Original Message----- > From: Sebastian Hesselbarth [mailto:sebastian.hesselbarth@xxxxxxxxx] > Sent: Wednesday, July 03, 2013 6:09 PM > To: Sascha Hauer > Cc: Inki Dae; 'Daniel Drake'; 'Jean-Francois Moine'; devicetree- > discuss@xxxxxxxxxxxxxxxx; 'Russell King'; dri-devel@xxxxxxxxxxxxxxxxxxxxx > Subject: Re: Best practice device tree design for display subsystems/DRM > > On 07/03/13 11:02, Sascha Hauer wrote: > > On Wed, Jul 03, 2013 at 05:57:18PM +0900, Inki Dae wrote: > >>> video { > >>> /* Single video card w/ multiple lcd controllers */ > >>> card0 { > >>> compatible = "marvell,armada-510-display"; > >>> reg = <0 0x3f000000 0x1000000>; /* video-mem hole */ > >>> /* later: linux,video-memory-size = <0x1000000>; */ > >>> marvell,video-devices = <&lcd0 &lcd1 &dcon>; > >>> }; > >>> > >>> /* OR: Multiple video card w/ single lcd controllers */ > >>> card0 { > >>> compatible = "marvell,armada-510-display"; > >>> ... > >>> marvell,video-devices = <&lcd0>; > >>> }; > >>> > >>> card1 { > >>> compatible = "marvell,armada-510-display"; > >>> ... > >>> marvell,video-devices = <&lcd1>; > >>> }; > >>> }; > >> > >> Sorry but I'd like to say that this cannot be used commonly. Shouldn't > you > >> really consider Linux framebuffer or other subsystems? The above dtsi > file > >> is specific to DRM subsystem. And I think the dtsi file has no any > >> dependency on certain subsystem so board dtsi file should be considered > for > >> all device drivers based on other subsystems: i.e., Linux framebuffer, > DRM, > >> and so no. So I *strongly* object to it. All we have to do is to keep > the > >> dtsi file as is, and to find other better way that can be used commonly > in > >> DRM. > > Sascha, Inki, > > can you clarify how the above will _not_ allow you to write a fb driver > exploiting the cardX nodes? > That's not whether we can write device driver or not. dtsi is common spot in other subsystems. Do you think the cardX node is meaningful to other subsystems? Thanks, Inki Dae > While lcd controller and dcon are physically available, the video card > is just a virtual combination of those. > > > +1 for not encoding the projected usecase of the graphics subsystem into > > the devicetree. Whether the two LCD controllers shall be used together > > or separately should not affect the devicetree. devicetree is about > > hardware description, not configuration. > > Have you had a look at gpio-leds? It _is_ actually a configuration of > GPIO to be used as LED triggers. IMHO DT is just fine for describing > even "virtual" hardware you make up out of existing devices. Without it > there is no way for the subsystems to determine the configuration. > > Regarding gpio-leds, how should the driver know the single gpio line > out of tens of available lines, if you do not use a virtual gpio led > node to describe it? > > Sebastian _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
