[Bug 59841] [IVB cpu eDP] panel is broken due to 657445fe86 (eDP bpp clamping)

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=59841

--- Comment #79 from jkp <jkp at iki.fi> ---
Added some debug messages to intel_bios.c:

    DRM_DEBUG_KMS("edp_support: %d\n", dev_priv->vbt.edp_support);
    DRM_DEBUG_KMS("SUPPORTS_EDP: %d\n", SUPPORTS_EDP(dev_priv->dev));

before the line:

    switch ((edp->color_depth >> (panel_type * 2)) & 3) {


Output says the edp_support flag is not set:

[drm:parse_edp], edp_support: 0
[drm:parse_edp], SUPPORTS_EDP: 0

A bug? No EDP support indicated by the device, but color_depth from edp is used
anyway.

Proposed fix, instead of:

    if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp)
              bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);

in intel_dp.c, check also for edp_support:

    if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp && dev_priv->vbt.edp_support)
              bpp = min_t(int, bpp, dev_priv->vbt.edp_bpp);

Will test.

Maybe other bogus edp info is also set in parse_edp due to ignoring the edp
support flag.

(This assuming I've understood the edp support flag correctly and it works; not
familiar with the code & panels, so could be I'm completely at the wrong track)

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the assignee for the bug.