drm: simple_kms_helper: Add mode_valid() callback support

The PL111 needs to filter valid modes based on memory bandwidth.
I guess it is a pretty simple operation, so we can still claim
the DRM KMS helper pipeline is simple after adding this (optional)
vtable callback.

Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180220072859.3386-1-linus.walleij@linaro.org

2 files changed, 29 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_simple_kms_helper.c b/drivers/gpu/drm/drm_simple_kms_helper.c
index 9d3f6b70812c..6c327fdbaaee 100644
--- a/drivers/gpu/drm/drm_simple_kms_helper.c
+++ b/drivers/gpu/drm/drm_simple_kms_helper.c
@@ -34,6 +34,20 @@ static const struct drm_encoder_funcs drm_simple_kms_encoder_funcs = {
         .destroy = drm_encoder_cleanup,
 };
 
+static enum drm_mode_status
+drm_simple_kms_crtc_mode_valid(struct drm_crtc *crtc,
+                               const struct drm_display_mode *mode)
+{
+        struct drm_simple_display_pipe *pipe;
+
+        pipe = container_of(crtc, struct drm_simple_display_pipe, crtc);
+        if (!pipe->funcs || !pipe->funcs->mode_valid)
+                /* Anything goes */
+                return MODE_OK;
+
+        return pipe->funcs->mode_valid(crtc, mode);
+}
+
 static int drm_simple_kms_crtc_check(struct drm_crtc *crtc,
                                      struct drm_crtc_state *state)
 {
@@ -72,6 +86,7 @@ static void drm_simple_kms_crtc_disable(struct drm_crtc *crtc,
 }
 
 static const struct drm_crtc_helper_funcs drm_simple_kms_crtc_helper_funcs = {
+        .mode_valid = drm_simple_kms_crtc_mode_valid,
         .atomic_check = drm_simple_kms_crtc_check,
         .atomic_enable = drm_simple_kms_crtc_enable,
         .atomic_disable = drm_simple_kms_crtc_disable,
diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h
index 6d9adbb46293..d9e4c3c3f009 100644
--- a/include/drm/drm_simple_kms_helper.h
+++ b/include/drm/drm_simple_kms_helper.h
@@ -22,6 +22,20 @@ struct drm_simple_display_pipe;
  */
 struct drm_simple_display_pipe_funcs {
         /**
+         * @mode_valid:
+         *
+         * This function is called to filter out valid modes from the
+         * suggestions suggested by the bridge or display. This optional
+         * hook is passed in when initializing the pipeline.
+         *
+         * RETURNS:
+         *
+         * drm_mode_status Enum
+         */
+        enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
+                                           const struct drm_display_mode *mode);
+
+        /**
          * @enable:
          *
          * This function should be used to enable the pipeline.