On Sun, 28 Aug 2016, Andrea Arcangeli <aarcange@xxxxxxxxxx> wrote:
> Skylake was already singled out, but it doesn't cover the XPS 13 L332X
> model which is based on IvyBridge.
>
> The commit that introduced the regression is
> 1d6da87a3241deb13d073c4125d19ed0e5a0c62c
That's a merge commit, the real one is
commit a05628195a0d9f3173dd9aa76f482aef692e46ee
Author: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Date: Mon Apr 11 10:23:51 2016 +0300
drm/i915: Get panel_type from OpRegion panel details
> The Skylake workaround for the regression was introduced in commit
> aeddda06c1a704bb97c8a7bfe7a472120193bd56
>
> Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_opregion.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> index adca262..ca17ab6 100644
> --- a/drivers/gpu/drm/i915/intel_opregion.c
> +++ b/drivers/gpu/drm/i915/intel_opregion.c
> @@ -1073,12 +1073,14 @@ intel_opregion_get_panel_type(struct drm_i915_private *dev_priv)
> }
>
> /*
> - * FIXME On Dell XPS 13 9350 the OpRegion panel type (0) gives us
> - * low vswing for eDP, whereas the VBT panel type (2) gives us normal
> - * vswing instead. Low vswing results in some display flickers, so
> - * let's simply ignore the OpRegion panel type on SKL for now.
> + * FIXME On Dell XPS 13 9350 and Dell XPS 13 L322X the
> + * OpRegion panel type (0) gives us low vswing for eDP,
> + * whereas the VBT panel type (2) gives us normal vswing
> + * instead. Low vswing results in some display flickers, so
> + * let's simply ignore the OpRegion panel type on SKL and
> + * IVYBRIDGE for now.
> */
If it's an Iybridge, there's no low vswing, and that explanation is
false. You can verify by trying i915.edp_vswing=1 or i915.edp_vswing=2
on an unpatched kernel.
Doesn't mean there can't be something else wrong with the mode you get
using a different panel_type. And this makes me wonder what the point is
in trying to patch up the commit instead of reverting.
BR,
Jani.
> - if (IS_SKYLAKE(dev_priv)) {
> + if (IS_SKYLAKE(dev_priv) || IS_IVYBRIDGE(dev_priv)) {
> DRM_DEBUG_KMS("Ignoring OpRegion panel type (%d)\n", ret - 1);
> return -ENODEV;
> }
> _______________________________________________
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--
Jani Nikula, Intel Open Source Technology Center
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