[PATCH 4.8 45/92] drm/i915/dp: Extend BDW DP audio workaround to GEN9 platforms

From: Greg Kroah-Hartman
Date: Thu Nov 17 2016 - 05:35:37 EST

4.8-stable review patch. If anyone has any objections, please let me know.


From: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>

commit 61e0c5438866d0e737937fc35d752538960e1e9f upstream.

According to BSpec, cdclk for BDW has to be not less than 432 MHz with DP
audio enabled, port width x4, and link rate HBR2 (5.4 GHz). With cdclk less
than 432 MHz, enabling audio leads to pipe FIFO underruns and displays
cycling on/off.

Let's apply this work around to GEN9 platforms too, as it fixes the same

v2: Move drm_device to drm_i915_private conversion

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97907
Cc: Libin Yang <libin.yang@xxxxxxxxxxxxxxx>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1478117601-19122-1-git-send-email-dhinakaran.pandiyan@xxxxxxxxx
(cherry picked from commit 9c7540241885838cfc7fa58c4a8bd75be0303ed1)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/gpu/drm/i915/intel_display.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9740,8 +9740,10 @@ static void bxt_modeset_commit_cdclk(str
static int bdw_adjust_min_pipe_pixel_rate(struct intel_crtc_state *crtc_state,
int pixel_rate)
+ struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
/* pixel rate mustn't exceed 95% of cdclk with IPS on BDW */
- if (crtc_state->ips_enabled)
+ if (IS_BROADWELL(dev_priv) && crtc_state->ips_enabled)
pixel_rate = DIV_ROUND_UP(pixel_rate * 100, 95);

/* BSpec says "Do not use DisplayPort with CDCLK less than
@@ -9783,7 +9785,7 @@ static int ilk_max_pixel_rate(struct drm

pixel_rate = ilk_pipe_pixel_rate(crtc_state);

- if (IS_BROADWELL(dev_priv))
+ if (IS_BROADWELL(dev_priv) || IS_GEN9(dev_priv))
pixel_rate = bdw_adjust_min_pipe_pixel_rate(crtc_state,