[RFC][PATCH 1/7] drm: Add drm_format_num_planes() utility function

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

This function returns the number of planes used by a specific pixel
format.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_crtc_helper.c |   33 +++++++++++++++++++++++++++++++++
 include/drm/drm_crtc.h            |    1 +
 include/drm/drm_crtc_helper.h     |    3 +++
 3 files changed, 37 insertions(+), 0 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc_helper.c b/drivers/gpu/drm/drm_crtc_helper.c
index 68011bb..db59561 100644
--- a/drivers/gpu/drm/drm_crtc_helper.c
+++ b/drivers/gpu/drm/drm_crtc_helper.c
@@ -1011,3 +1011,36 @@ void drm_helper_hpd_irq_event(struct drm_device *dev)
 		queue_delayed_work(system_nrt_wq, &dev->mode_config.output_poll_work, 0);
 }
 EXPORT_SYMBOL(drm_helper_hpd_irq_event);
+
+
+/**
+ * drm_format_num_planes - get the number of planes for format
+ * @format: pixel format (V4L2_PIX_FMT_*)
+ *
+ * See linux/videodev2.h for valid values of @format.
+ *
+ * RETURNS:
+ * The number of planes used by the specified pixel format.
+ */
+int drm_format_num_planes(uint32_t format)
+{
+	/* FIXME add all planar formats. */
+
+	switch (format) {
+	case V4L2_PIX_FMT_YUV410:
+	case V4L2_PIX_FMT_YVU410:
+	case V4L2_PIX_FMT_YUV420:
+	case V4L2_PIX_FMT_YVU420:
+	case V4L2_PIX_FMT_YUV411P:
+	case V4L2_PIX_FMT_YUV422P:
+		return 3;
+	case V4L2_PIX_FMT_NV12:
+	case V4L2_PIX_FMT_NV21:
+	case V4L2_PIX_FMT_NV16:
+	case V4L2_PIX_FMT_NV61:
+		return 2;
+	default:
+		return 1;
+	}
+}
+EXPORT_SYMBOL(drm_format_num_planes);
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 49dc288..736d68d 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -902,4 +902,5 @@ extern int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
 				    void *data, struct drm_file *file_priv);
 extern int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
 				      void *data, struct drm_file *file_priv);
+
 #endif /* __DRM_CRTC_H__ */
diff --git a/include/drm/drm_crtc_helper.h b/include/drm/drm_crtc_helper.h
index b4abb33..20a43f7 100644
--- a/include/drm/drm_crtc_helper.h
+++ b/include/drm/drm_crtc_helper.h
@@ -146,4 +146,7 @@ extern void drm_helper_hpd_irq_event(struct drm_device *dev);
 
 extern void drm_kms_helper_poll_disable(struct drm_device *dev);
 extern void drm_kms_helper_poll_enable(struct drm_device *dev);
+
+extern int drm_format_num_planes(uint32_t format);
+
 #endif
-- 
1.7.3.4