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drm/i915: Reduce CHV DDL multiplier to 16/8 

Apparently we must yet halve the DDL drain latency from what we're
using currently. This little nugget is not in any spec, but came
down through the grapevine.

This makes the displays a bit more stable. Not quite fully stable but at
least they don't fall over immediately on driver load.

v2: Update high_precision in valleyview_update_sprite_wm() too (Jesse)

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Ville Syrjälä 2015-03-05 21:19:41 +02:00 committed by Daniel Vetter
parent 48572edd9d
commit edf6056014
2 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/gpu/drm/i915/i915_reg.h
View File

@ -4205,6 +4205,7 @@ enum skl_disp_power_wells {
#define DSPFW_PLANEA_WM1_HI_MASK (1<<0)
/* drain latency register values*/
#define DRAIN_LATENCY_PRECISION_8 8
#define DRAIN_LATENCY_PRECISION_16 16
#define DRAIN_LATENCY_PRECISION_32 32
#define DRAIN_LATENCY_PRECISION_64 64

8
drivers/gpu/drm/i915/intel_pm.c
View File

@ -756,8 +756,8 @@ static bool vlv_compute_drain_latency(struct drm_crtc *crtc,
entries = DIV_ROUND_UP(clock, 1000) * pixel_size;
if (IS_CHERRYVIEW(dev))
*prec_mult = (entries > 128) ? DRAIN_LATENCY_PRECISION_32 :
DRAIN_LATENCY_PRECISION_16;
*prec_mult = (entries > 32) ? DRAIN_LATENCY_PRECISION_16 :
DRAIN_LATENCY_PRECISION_8;
else
*prec_mult = (entries > 128) ? DRAIN_LATENCY_PRECISION_64 :
DRAIN_LATENCY_PRECISION_32;
@ -787,7 +787,7 @@ static void vlv_update_drain_latency(struct drm_crtc *crtc)
enum pipe pipe = intel_crtc->pipe;
int plane_prec, prec_mult, plane_dl;
const int high_precision = IS_CHERRYVIEW(dev) ?
DRAIN_LATENCY_PRECISION_32 : DRAIN_LATENCY_PRECISION_64;
DRAIN_LATENCY_PRECISION_16 : DRAIN_LATENCY_PRECISION_64;
plane_dl = I915_READ(VLV_DDL(pipe)) & ~(DDL_PLANE_PRECISION_HIGH |
DRAIN_LATENCY_MASK | DDL_CURSOR_PRECISION_HIGH |
@ -986,7 +986,7 @@ static void valleyview_update_sprite_wm(struct drm_plane *plane,
int sprite_dl;
int prec_mult;
const int high_precision = IS_CHERRYVIEW(dev) ?
DRAIN_LATENCY_PRECISION_32 : DRAIN_LATENCY_PRECISION_64;
DRAIN_LATENCY_PRECISION_16 : DRAIN_LATENCY_PRECISION_64;
sprite_dl = I915_READ(VLV_DDL(pipe)) & ~(DDL_SPRITE_PRECISION_HIGH(sprite) |
(DRAIN_LATENCY_MASK << DDL_SPRITE_SHIFT(sprite)));