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drm/i915: Refuse modes with hdisplay==4096 on pre-HSW DP 

The DP port/pipe goes wonky if we try to use timings with
hdisplay==4096 on pre-HSW platforms. The link fails to train
and the pipe may not signal vblank interrupts. On HDMI such at
mode works just fine (tested on ELK/SNB/CHV). So let's refuse
such modes on DP on older platforms.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190718144340.1114-1-ville.syrjala@linux.intel.com
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
This commit is contained in:
Ville Syrjälä 2019-07-18 17:43:39 +03:00
parent c08f995a28
commit 98c93394ba
1 changed files with 25 additions and 0 deletions
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25
drivers/gpu/drm/i915/display/intel_dp.c
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@ -591,6 +591,25 @@ static u8 intel_dp_dsc_get_slice_count(struct intel_dp *intel_dp,
return 0;
}
static bool intel_dp_hdisplay_bad(struct drm_i915_private *dev_priv,
int hdisplay)
{
/*
* Older platforms don't like hdisplay==4096 with DP.
*
* On ILK/SNB/IVB the pipe seems to be somewhat running (scanline
* and frame counter increment), but we don't get vblank interrupts,
* and the pipe underruns immediately. The link also doesn't seem
* to get trained properly.
*
* On CHV the vblank interrupts don't seem to disappear but
* otherwise the symptoms are similar.
*
* TODO: confirm the behaviour on HSW+
*/
return hdisplay == 4096 && !HAS_DDI(dev_priv);
}
static enum drm_mode_status
intel_dp_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
@ -626,6 +645,9 @@ intel_dp_mode_valid(struct drm_connector *connector,
max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
mode_rate = intel_dp_link_required(target_clock, 18);
if (intel_dp_hdisplay_bad(dev_priv, mode->hdisplay))
return MODE_H_ILLEGAL;
/*
* Output bpp is stored in 6.4 format so right shift by 4 to get the
* integer value since we support only integer values of bpp.
@ -2345,6 +2367,9 @@ intel_dp_compute_config(struct intel_encoder *encoder,
if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
return -EINVAL;
if (intel_dp_hdisplay_bad(dev_priv, adjusted_mode->crtc_hdisplay))
return -EINVAL;
ret = intel_dp_compute_link_config(encoder, pipe_config, conn_state);
if (ret < 0)
return ret;