[Bug 75880] [i915 Bayley Bay] Graphics shake/jitter observed when seen on DP monitor

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=75880

--- Comment #5 from arun <achandran at mvista.com> ---
Hi,


The below patch solves the problem for me

########################################
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 41bdac4..ad1d824 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -844,12 +844,6 @@ intel_dp_compute_config(struct intel_encoder *encoder,
        /* Walk through all bpp values. Luckily they're all nicely spaced with
2
         * bpc in between. */
        bpp = pipe_config->pipe_bpp;
-       if (is_edp(intel_dp) && dev_priv->vbt.edp_bpp &&
-           dev_priv->vbt.edp_bpp < bpp) {
-               DRM_DEBUG_KMS("clamping bpp for eDP panel to BIOS-provided
%i\n",
-                             dev_priv->vbt.edp_bpp);
-               bpp = dev_priv->vbt.edp_bpp;
-       }

        for (; bpp >= 6*3; bpp -= 2*3) {
                mode_rate = intel_dp_link_required(adjusted_mode->crtc_clock,

###########################################


In the case of VGA + DP overriding of BIOS provided max bpp is not happening as
 intel_dp_get_config() is called after calling intel_dp_compute_config(). That
function overrides pipe bpp with BIOS provided one.


I think it happens because the when both DP and VGA is connected, DP is powered
on lately and intel_dp_get_hw_state() returns false so 
intel_modeset_readout_hw_state() is not calling intel_dp_get_config() during
the booting.


Regards,
Arun C

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