diff options
Diffstat (limited to 'drivers/gpu/drm/i915/intel_display.c')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_display.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 3fadb5358858..748ed50c55ca 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -2005,7 +2005,21 @@ static void igd_enable_cxsr(struct drm_device *dev, unsigned long clock, return; } -const static int latency_ns = 3000; /* default for non-igd platforms */ +/* + * Latency for FIFO fetches is dependent on several factors: + * - memory configuration (speed, channels) + * - chipset + * - current MCH state + * It can be fairly high in some situations, so here we assume a fairly + * pessimal value. It's a tradeoff between extra memory fetches (if we + * set this value too high, the FIFO will fetch frequently to stay full) + * and power consumption (set it too low to save power and we might see + * FIFO underruns and display "flicker"). + * + * A value of 5us seems to be a good balance; safe for very low end + * platforms but not overly aggressive on lower latency configs. + */ +const static int latency_ns = 5000; static int intel_get_fifo_size(struct drm_device *dev, int plane) { |