From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/i915/intel_pm.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c index 45f71e6..5b683e8 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; } -- 1.8.5.5 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
