[PATCH i-g-t v8 4/9] lib/igt_fb: Add helper to get bpc from DRM fourcc

[Sowmiya S <sowmiya.s@intel.com>]

Introduce igt_drm_format_get_bpc, which returns
the nominal bits per color channel (BPC) for
common RGB DRM fourcc formats.

Signed-off-by: Sowmiya S <sowmiya.s@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
---
 lib/igt_fb.c | 33 +++++++++++++++++++++++++++++++++
 lib/igt_fb.h |  1 +
 2 files changed, 34 insertions(+)

diff --git a/lib/igt_fb.c b/lib/igt_fb.c
index 3a1553d48..b3575d266 100644
--- a/lib/igt_fb.c
+++ b/lib/igt_fb.c
@@ -5083,6 +5083,39 @@ int igt_fb_get_fnv1a_crc(struct igt_fb *fb, igt_crc_t *crc)
 	return 0;
 }
 
+/**
+ * igt_drm_format_get_bpc: Return bits-per-channel for a DRM fourcc format
+ * @drm_format: drm fourcc code
+ *
+ * Returns the nominal bits-per-color-channel (BPC) for the given @drm_format.
+ * This helper is intended for RGB formats and currently covers common packed
+ * and planar RGB(A/X) variants. Non-RGB formats are not yet handled.
+ * Extend as needed to cover additional FOURCCs (including YUV) by
+ * adding explicit cases.
+ */
+int igt_drm_format_get_bpc(uint32_t drm_format)
+{
+	switch (drm_format) {
+	case DRM_FORMAT_XRGB8888:
+	case DRM_FORMAT_ARGB8888:
+	case DRM_FORMAT_XBGR8888:
+	case DRM_FORMAT_ABGR8888:
+		return 8;
+	case DRM_FORMAT_XRGB2101010:
+	case DRM_FORMAT_ARGB2101010:
+	case DRM_FORMAT_XBGR2101010:
+	case DRM_FORMAT_ABGR2101010:
+		return 10;
+	case DRM_FORMAT_XRGB16161616F:
+	case DRM_FORMAT_XBGR16161616F:
+	case DRM_FORMAT_ARGB16161616F:
+	case DRM_FORMAT_ABGR16161616F:
+		return 16;
+	default:
+		return -1;
+	}
+}
+
 /**
  * igt_format_is_yuv:
  * @drm_format: drm fourcc
diff --git a/lib/igt_fb.h b/lib/igt_fb.h
index 8e5907dab..844b27ff2 100644
--- a/lib/igt_fb.h
+++ b/lib/igt_fb.h
@@ -222,6 +222,7 @@ int igt_cairo_printf_line(cairo_t *cr, enum igt_text_align align,
 /* helpers to handle drm fourcc codes */
 uint32_t igt_bpp_depth_to_drm_format(int bpp, int depth);
 uint32_t igt_drm_format_to_bpp(uint32_t drm_format);
+int igt_drm_format_get_bpc(uint32_t drm_format);
 const char *igt_format_str(uint32_t drm_format);
 bool igt_fb_supported_format(uint32_t drm_format);
 bool igt_format_is_yuv(uint32_t drm_format);
-- 
2.43.0