On Tue, Aug 25, 2015 at 05:41:19PM +0800, Yakir Yang wrote:

Hi Thierry,

在 2015/8/25 17:12, Thierry Reding 写道:

quoted

On Mon, Aug 24, 2015 at 09:48:27AM -0500, Rob Herring wrote:

quoted

On Mon, Aug 24, 2015 at 7:57 AM, Russell King - ARM Linux
[off-list ref] wrote:

quoted

On Sun, Aug 23, 2015 at 06:23:14PM -0500, Rob Herring wrote:

quoted

On Wed, Aug 19, 2015 at 9:50 AM, Yakir Yang [off-list ref] wrote:

quoted

+       -analogix,color-depth:
+               number of bits per colour component.
+                       COLOR_6 = 0, COLOR_8 = 1, COLOR_10 = 2, COLOR_12 = 3

This seems pretty generic. Just use 6, 8, 10, or 12 for values. And
drop the vendor prefix.

Please think about this some more.  What does "color-depth" mean?  Does it
mean the number of bits per colour _component_, or does it mean the total
number of bits to represent a particular colour.  It's confusing as it
stands.

Then "component-color-bpp" perhaps?

There should be no need to have this in DT at all. The BPC is a property
of the attached panel and it should come from the panel (either the
panel driver or parsed from EDID if available).

Actually I have send an email about this one to you in version 2, just past
from that email:

"samsung,color_space" and "samsung,color-depth"

The drm_display_info's color_formats and bpc indicate the monitor display
ability, but
the edp driver could not take it as input video format directly.

For example, with my DP TV I would found "RGB444 & YCRCB422 & & YCRCB444"
support in drm_display_info.color_formats and 16bit bpc support, but RK3288
crtc
driver could only output RGB & ITU formats, so finally analogix_dp-rockchip
driver
config crtc to RGBaaa 10bpc mode.

In this sutiation, the analogix_dp core driver would pazzled by the
drm_display_info,
can't chose the right color_space and bpc.

And this is the place that confused me, wish you could give some ideas about
this one :-)

Your display driver should choose whatever it is capable of outputting.
If the display reports that it can do 16 bits-per-color, but your
display driver can't do it, then it should choose a configuration that
it supports. Similarily for the color encodings. If you can't generate
YCrCb444 with your hardware, then it's the driver's job to know about
that and select the next appropriate configuration.

But hard-coding this is not the right solution because the value in DT
may end up conflicting with what the display reports.

Thierry