[Bug 94921] Remove illogical/bogus "Automatic" mode from "Broadcast RGB" property

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=94921

--- Comment #19 from Nicholas Stommel (nicholas.stommel at gmail.com) ---
 (In reply to Tom Yan)
> Essentially your patch means to avoid using limited range as default for
> "all DP in reality", which is one of the approaches I proposed, so good luck
> having Intel accpeting it. (No offense but the extra check makes less sense
> than just equate auto to full.)

Oh...wait. My logic was incorrect indeed. Tom is basically right here, as what
is CURRENTLY happening in the conditional statement means ANY DP 18bpp display
(and with my small patch ANY DP 24bpp display) will result in an immediate
short-circuit boolean 'false' value, setting pipe_config->limited_color_range =
false. See the unpatched condition below: 

pipe_config->limited_color_range =
  bpp != 18 &&
  drm_default_rgb_quant_range(adjusted_mode) ==
  HDMI_QUANTIZATION_RANGE_LIMITED;

On further inspection, Intel currently isn't even testing whether displays with
18bpp adhere to the CEA/VESA spec, as the function
drm_default_rgb_quant_range(...) is never actually executed. Which just makes
me confused. Why should those of us with 24bpp True Color or 30+bpp HDR
displays *not* be getting full-range color? It doesn't even make sense. So now
I suppose we are right back where we started at bug #94921.

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