diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2014-09-05 22:54:13 +0400 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-09-19 16:41:11 +0400 |
| commit | d6feb1962d08890080cbce080a3d73e1035f0a3d (patch) | |
| tree | 935eaedbe92ac774c7e923c95f776c9719d269ab /drivers/gpu/drm/i915 | |
| parent | 1c4e02746147cef8853142a7c71efcb2b9660aed (diff) | |
| download | linux-d6feb1962d08890080cbce080a3d73e1035f0a3d.tar.xz | |
drm/i915: Limit the watermark to at least 8 entries on gen2/3
830 is very unhappy of the watermark value is too low (indicating a very
high watermark in fact, ie. memory fetch will occur with an almost full
FIFO). Limit the watermark value to at least 8 cache lines.
That also matches the burst size we use on most platforms. BSpec seems
to indicate we should limit the watermark to 'burst size + 1'. But on
gen4 we already use a hardcoded 8 as the watermark value (as the spec
says we should), so just use 8 as the limit on gen2/3 as well.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/i915')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_pm.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 45f71e6dc544..675e8a2ce988 100644 --- a/drivers/gpu/drm/i915/intel_pm.c +++ b/drivers/gpu/drm/i915/intel_pm.c @@ -1070,6 +1070,17 @@ static unsigned long intel_calculate_wm(unsigned long clock_in_khz, wm_size = wm->max_wm; if (wm_size <= 0) wm_size = wm->default_wm; + + /* + * Bspec seems to indicate that the value shouldn't be lower than + * 'burst size + 1'. Certainly 830 is quite unhappy with low values. + * Lets go for 8 which is the burst size since certain platforms + * already use a hardcoded 8 (which is what the spec says should be + * done). + */ + if (wm_size <= 8) + wm_size = 8; + return wm_size; } |