[PATCH/RFC 6/6] drm: Make the CRTC gamma_set operation optional

[Laurent Pinchart]

Drivers for hardware without gamma support should not be forced to
implement a no-op gamma set operation.

Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Cc: Rob Clark <rob.clark at linaro.org>
---
 drivers/gpu/drm/drm_crtc.c          |    5 +++++
 drivers/gpu/drm/drm_fb_helper.c     |    3 +++
 drivers/staging/omapdrm/omap_crtc.c |    7 -------
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index bfc9b86..aa80d4a 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -3173,6 +3173,11 @@ int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 	}
 	crtc = obj_to_crtc(obj);
 
+	if (crtc->funcs->gamma_set == NULL) {
+		ret = -ENOSYS;
+		goto out;
+	}
+
 	/* memcpy into gamma store */
 	if (crtc_lut->gamma_size != crtc->gamma_size) {
 		ret = -EINVAL;
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index bd92616..f0b81d7 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -136,6 +136,9 @@ static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)
 {
 	uint16_t *r_base, *g_base, *b_base;
 
+	if (crtc->funcs->gamma_set == NULL)
+		return;
+
 	r_base = crtc->gamma_store;
 	g_base = r_base + crtc->gamma_size;
 	b_base = g_base + crtc->gamma_size;
diff --git a/drivers/staging/omapdrm/omap_crtc.c b/drivers/staging/omapdrm/omap_crtc.c
index 490a7f1..8b864af 100644
--- a/drivers/staging/omapdrm/omap_crtc.c
+++ b/drivers/staging/omapdrm/omap_crtc.c
@@ -36,12 +36,6 @@ struct omap_crtc {
 	struct drm_framebuffer *old_fb;
 };
 
-static void omap_crtc_gamma_set(struct drm_crtc *crtc,
-		u16 *red, u16 *green, u16 *blue, uint32_t start, uint32_t size)
-{
-	/* not supported.. at least not yet */
-}
-
 static void omap_crtc_destroy(struct drm_crtc *crtc)
 {
 	struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
@@ -198,7 +192,6 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
 }
 
 static const struct drm_crtc_funcs omap_crtc_funcs = {
-	.gamma_set = omap_crtc_gamma_set,
 	.set_config = drm_crtc_helper_set_config,
 	.destroy = omap_crtc_destroy,
 	.page_flip = omap_crtc_page_flip_locked,
-- 
1.7.3.4