[PATCH v2 5/8] drm/format-helper: Add generic conversion to 8-bit formats

[Thomas Zimmermann <tzimmermann@suse.de>]

Add drm_fb_xfrm_line_32to8() to implement conversion from 32-bit
pixels to 8-bit pixels. The pixel-conversion is specified by the
given callback parameter. Mark the helper as always_inline to avoid
overhead from function calls.

Then implement all existing line-conversion functions with the new
generic call and the respective pixel-conversion helper.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
---
 drivers/gpu/drm/drm_format_helper.c   | 38 ++++++++++-----------------
 drivers/gpu/drm/drm_format_internal.h | 17 ++++++++++++
 2 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index aecf55c1fc6ba..a926aa6671fcd 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -246,6 +246,18 @@ static int drm_fb_xfrm(struct iosys_map *dst,
 				     xfrm_line);
 }
 
+static __always_inline void drm_fb_xfrm_line_32to8(void *dbuf, const void *sbuf,
+						   unsigned int pixels,
+						   u32 (*xfrm_pixel)(u32))
+{
+	u8 *dbuf8 = dbuf;
+	const __le32 *sbuf32 = sbuf;
+	const __le32 *send32 = sbuf32 + pixels;
+
+	while (sbuf32 < send32)
+		*dbuf8++ = xfrm_pixel(le32_to_cpup(sbuf32++));
+}
+
 static __always_inline void drm_fb_xfrm_line_32to16(void *dbuf, const void *sbuf,
 						    unsigned int pixels,
 						    u32 (*xfrm_pixel)(u32))
@@ -411,17 +423,7 @@ EXPORT_SYMBOL(drm_fb_swab);
 
 static void drm_fb_xrgb8888_to_rgb332_line(void *dbuf, const void *sbuf, unsigned int pixels)
 {
-	u8 *dbuf8 = dbuf;
-	const __le32 *sbuf32 = sbuf;
-	unsigned int x;
-	u32 pix;
-
-	for (x = 0; x < pixels; x++) {
-		pix = le32_to_cpu(sbuf32[x]);
-		dbuf8[x] = ((pix & 0x00e00000) >> 16) |
-			   ((pix & 0x0000e000) >> 11) |
-			   ((pix & 0x000000c0) >> 6);
-	}
+	drm_fb_xfrm_line_32to8(dbuf, sbuf, pixels, drm_pixel_xrgb8888_to_rgb332);
 }
 
 /**
@@ -879,19 +881,7 @@ EXPORT_SYMBOL(drm_fb_xrgb8888_to_argb2101010);
 
 static void drm_fb_xrgb8888_to_gray8_line(void *dbuf, const void *sbuf, unsigned int pixels)
 {
-	u8 *dbuf8 = dbuf;
-	const __le32 *sbuf32 = sbuf;
-	unsigned int x;
-
-	for (x = 0; x < pixels; x++) {
-		u32 pix = le32_to_cpu(sbuf32[x]);
-		u8 r = (pix & 0x00ff0000) >> 16;
-		u8 g = (pix & 0x0000ff00) >> 8;
-		u8 b =  pix & 0x000000ff;
-
-		/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
-		*dbuf8++ = (3 * r + 6 * g + b) / 10;
-	}
+	drm_fb_xfrm_line_32to8(dbuf, sbuf, pixels, drm_pixel_xrgb8888_to_r8_bt601);
 }
 
 /**
diff --git a/drivers/gpu/drm/drm_format_internal.h b/drivers/gpu/drm/drm_format_internal.h
index 4f20b63cb6f60..9f857bfa368d1 100644
--- a/drivers/gpu/drm/drm_format_internal.h
+++ b/drivers/gpu/drm/drm_format_internal.h
@@ -35,6 +35,23 @@
  * Conversions from XRGB8888
  */
 
+static inline u32 drm_pixel_xrgb8888_to_r8_bt601(u32 pix)
+{
+	u32 r = (pix & 0x00ff0000) >> 16;
+	u32 g = (pix & 0x0000ff00) >> 8;
+	u32 b =  pix & 0x000000ff;
+
+	/* ITU-R BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
+	return (3 * r + 6 * g + b) / 10;
+}
+
+static inline u32 drm_pixel_xrgb8888_to_rgb332(u32 pix)
+{
+	return ((pix & 0x00e00000) >> 16) |
+	       ((pix & 0x0000e000) >> 11) |
+	       ((pix & 0x000000c0) >> 6);
+}
+
 static inline u32 drm_pixel_xrgb8888_to_rgb565(u32 pix)
 {
 	return ((pix & 0x00f80000) >> 8) |
-- 
2.48.1