diff options
Diffstat (limited to 'drivers/gpu/drm/i915')
| -rw-r--r-- | drivers/gpu/drm/i915/intel_runtime_pm.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c index 3fffbfe4521d..53a6eaa9671a 100644 --- a/drivers/gpu/drm/i915/intel_runtime_pm.c +++ b/drivers/gpu/drm/i915/intel_runtime_pm.c @@ -542,6 +542,29 @@ void gen9_sanitize_dc_state(struct drm_i915_private *dev_priv) dev_priv->csr.dc_state = val; } +/** + * gen9_set_dc_state - set target display C power state + * @dev_priv: i915 device instance + * @state: target DC power state + * - DC_STATE_DISABLE + * - DC_STATE_EN_UPTO_DC5 + * - DC_STATE_EN_UPTO_DC6 + * - DC_STATE_EN_DC9 + * + * Signal to DMC firmware/HW the target DC power state passed in @state. + * DMC/HW can turn off individual display clocks and power rails when entering + * a deeper DC power state (higher in number) and turns these back when exiting + * that state to a shallower power state (lower in number). The HW will decide + * when to actually enter a given state on an on-demand basis, for instance + * depending on the active state of display pipes. The state of display + * registers backed by affected power rails are saved/restored as needed. + * + * Based on the above enabling a deeper DC power state is asynchronous wrt. + * enabling it. Disabling a deeper power state is synchronous: for instance + * setting %DC_STATE_DISABLE won't complete until all HW resources are turned + * back on and register state is restored. This is guaranteed by the MMIO write + * to DC_STATE_EN blocking until the state is restored. + */ static void gen9_set_dc_state(struct drm_i915_private *dev_priv, uint32_t state) { uint32_t val; |