Re: eDP display control registers in Linux kernel

[Jani Nikula <jani.nikula@intel.com>]

On Mon, 23 Feb 2015, Michael Leuchtenburg <michael@slashhome.org> wrote:
> I'm certain that it has dynamic backlight control of some sort, as the
> brightness varies based on content. I'm also sure it has an eDP panel, and
> an Intel graphics adapter. I'm not certain that DPCD will let me adjust it,
> or how to check, though the ChromeOS patch seems to assume that intel + edp
> -> DBC adjustable via DPCD.

I just sent a patch to dump the DPCD in debugfs [1]. Please apply that
on top of v4.0-rc1 or drm-intel-nightly, *and* add the following patch
on top. Please share the contents of
/sys/kernel/debug/dri/0/eDP-1/i915_dpcd running that (I assume the name
will be eDP-1).

BR,
Jani.


[1] http://patchwork.freedesktop.org/patch/43332


diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 451ef456c25f..c66b0679d6e2 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -4672,6 +4672,9 @@ static const struct dpcd_block i915_dpcd_debug[] = {
 	{ .offset = DP_SINK_COUNT, .end = DP_ADJUST_REQUEST_LANE2_3 },
 	{ .offset = DP_SET_POWER },
 	{ .offset = DP_EDP_DPCD_REV },
+	{ .offset = 0x701, .end = 0x704 },
+	{ .offset = 0x720, .end = 0x72f },
+	{ .offset = 0x732, .end = 0x733 },
 };
 
 static int i915_dpcd_show(struct seq_file *m, void *data)

-- 
Jani Nikula, Intel Open Source Technology Center
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