Re: [PATCH, RFC] displaymodes in devicetree

On Wed, Jun 27, 2012 at 06:16:12AM -1000, Mitch Bradley wrote:

On 6/27/2012 2:43 AM, Sascha Hauer wrote:

quoted

Hi All,

I'd like to have a possibility to describe fixed display modes in the
devicetree. This topic has been discussed before here:

https://lists.ozlabs.org/pipermail/linuxppc-dev/2010-February/080683.html

The result at that time was that EDID data should be considered to use
as this is a format that already exists. I want to come back to this
topic since:

- EDID data is a binary format and as such quite inconvenient to handle.
  There exist several tools to parse EDID data, but I'm not aware of any
  (open source) tool which can generate EDID data.
- EDID blobs are hard to modify and hard to review in patches.
- EDID is designed to describe multiple modes, but fixed displays
  usually only support a single fixed mode.

There are several ways of describing the mode, for this patch I chose to
use the format (and naming) used by the Linux Framebuffer Layer as this
is the only description which does not allow for inconsistent modes. I
added the most common flags like [v|h]sync_active_high. Others can be
added, but these flags are pretty much agreed upon and won't be
superseeded with other flags. The mode from the devicetree can be
converted to the most common modes used in Linux, struct fb_videomode
and struct drm_display_mode.

Comments welcome

I like the general approach and the set of names.  The separators
inside the names should be hyphen (-) not underscore (_), following
the usual device tree convention.  The rationale for that convention
is to follow natural-language usage, not the identifier constraints
of programming languages based on algebraic expressions.

Good to hear that this is the convention for devicetree, I like
hyphens better aswell. Will change.

Sascha

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