drm/i915: Document that the pll->mode_set hook is optional

The WRPLLs won't use them.

Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 3d8783831e85..26982d12039f 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -206,6 +206,8 @@ struct intel_shared_dpll {
         /* should match the index in the dev_priv->shared_dplls array */
         enum intel_dpll_id id;
         struct intel_dpll_hw_state hw_state;
+        /* The mode_set hook is optional and should be used together with the
+         * intel_prepare_shared_dpll function. */
         void (*mode_set)(struct drm_i915_private *dev_priv,
                          struct intel_shared_dpll *pll);
         void (*enable)(struct drm_i915_private *dev_priv,