Re: [PATCH] dt-bindings: simplefb: Document naming scheme for pre-populated simplefb nodes

Hi,

On 11/14/2014 10:12 AM, Grant Likely wrote:

On Fri, Nov 14, 2014 at 9:02 AM, Hans de Goede [off-list ref] wrote:

quoted

Since we advice to use pre-populated simeplfb nodes in dt files, where the
firmware then only needs to fill in the mode info + address and enable it,
we should also specify how these pre-populated nodes should be named so
that the firmware can find and enable the right one.

Signed-off-by: Hans de Goede <redacted>
---
 Documentation/devicetree/bindings/video/simple-framebuffer.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
index c548f33..01dc948 100644
--- a/Documentation/devicetree/bindings/video/simple-framebuffer.txt
+++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt

@@ -29,6 +29,13 @@ enable them. This way if e.g. later on support for more display clocks get
 added, the simplefb nodes will already contain this info and the firmware
 does not need to be updated.

+If pre-filled framebuffer nodes are used, they should be named
+"framebuffer#-<output>", e.g. "framebuffer0-hdmi". The output should be
+included in the name since different outputs typically require different
+clocks and the clocks are part of the pre-populated nodes. The firmware must
+rename the nodes to the standard "framebuffer@<address>" using the runtime
+chosen address when enabling the nodes.

-<output> should be optional, an only used when there are multiple options.

Right, notice the "should be named", I would rather leave it at that then
complicate the wording by adding something about only use -output when there
are multiple options.

Something we've not talked about is how to handle a framebuffer that
has been set up with mirrored displays. Does that case matter?

It is bound to happen sooner or later I guess, but it is still just a single
framebuffer, so from the simplefb kernel driver pov it does not matter, it really
is just another variant on the -<output> theme where there happen to be 2 outputs
active at the same time.

Regards,

Hans

g.