On Tue, Jul 15, 2014 at 12:20:02PM +0200, Laurent Pinchart wrote: > Hi Boris, > > On Tuesday 15 July 2014 12:06:19 Boris BREZILLON wrote: > > On Mon, 14 Jul 2014 12:05:43 +0200 Thierry Reding wrote: > > > On Mon, Jul 07, 2014 at 06:42:59PM +0200, Boris BREZILLON wrote: > > > > The Atmel HLCDC (HLCD Controller) IP available on some Atmel SoCs (i.e. > > > > at91sam9n12, at91sam9x5 family or sama5d3 family) provides a display > > > > controller device. > > > > > > > > The HLCDC block provides a single RGB output port, and only supports LCD > > > > panels connection to LCD panels for now. > > > > > > > > The atmel,panel property link the HLCDC RGB output with the LCD panel > > > > connected on this port (note that the HLCDC RGB connector implementation > > > > makes use of the DRM panel framework). > > > > > > > > Connection to other external devices (DRM bridges) might be added later > > > > by mean of a new atmel,xxx (atmel,bridge) property. > > > > > > > > Signed-off-by: Boris BREZILLON <boris.brezillon@xxxxxxxxxxxxxxxxxx> > > > > --- > > > > > > > > .../devicetree/bindings/drm/atmel-hlcdc-dc.txt | 59 +++++++++++++++ > > > > 1 file changed, 59 insertions(+) > > > > create mode 100644 > > > > Documentation/devicetree/bindings/drm/atmel-hlcdc-dc.txt > > [snip] > > > > > + - atmel,panel: Should contain a phandle with 2 parameters. > > > > + The first cell is a phandle to a DRM panel device > > > > + The second cell encodes the RGB mode, which can take the following > > > > values: + * 0: RGB444 > > > > + * 1: RGB565 > > > > + * 2: RGB666 > > > > + * 3: RGB888 > > > > > > These are properties of the panel and should be obtained from the panel > > > directly rather than an additional cell in this specifier. > > > > Okay. > > What's the preferred way of doing this ? > > What about defining an rgb-mode property in the panel node. > > You could do that, but it won't help you much, as the HLCDC driver must not > parse properties from the panel node. You should instead extend the drm_panel > API with a function to retrieve panel properties. The HLCDC driver will then > query the panel driver at runtime for the interface type. The panel driver > will get the information from hardcoded data in the driver, from DT or > possibly in some cases by querying the panel hardware directly. My preference for this would be that we either add this to some existing structure (struct drm_display_info seems like a good candidate) or if the number of parameters grows out of hands, then maybe even introduce a new type of device that's specific for the interface. DRM panels are an abstraction for panels, that is, interface-agnostic, and if we start exposing interface specific parameters things will start to become very unwieldy. Thierry
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