drm/gud: Fix endianness in gud_xrgb8888_to_color() helper

DRM formats are defined to be little-endian, unless the
DRM_FORMAT_BIG_ENDIAN flag is set.  Hence when converting from one
format to another, multi-byte pixel values loaded from memory must be
converted from little-endian to host-endian.  Conversely, multi-byte
pixel values written to memory must be converted from host-endian to
little-endian.  Currently only drm_fb_xrgb8888_to_rgb332_line() includes
endianness handling.

Fix gud_xrgb8888_to_color() on big-endian platforms by adding the
missing endianness handling.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/b47589ed5d8ca44e0956684412e3f16f3227f887.1657300532.git.geert@linux-m68k.org

diff --git a/drivers/gpu/drm/gud/gud_pipe.c b/drivers/gpu/drm/gud/gud_pipe.c
index 4873f97..d42592f 100644 (file)
--- a/drivers/gpu/drm/gud/gud_pipe.c
+++ b/drivers/gpu/drm/gud/gud_pipe.c
@@ -105,7 +105,8 @@ static size_t gud_xrgb8888_to_color(u8 *dst, const struct drm_format_info *forma
        unsigned int bits_per_pixel = 8 / block_width;
        u8 r, g, b, pix, *block = dst; /* Assign to silence compiler warning */
        unsigned int x, y, width;
-       u32 *pix32;
+       __le32 *sbuf32;
+       u32 pix32;
        size_t len;
 
        /* Start on a byte boundary */
@@ -114,8 +115,8 @@ static size_t gud_xrgb8888_to_color(u8 *dst, const struct drm_format_info *forma
        len = drm_format_info_min_pitch(format, 0, width) * drm_rect_height(rect);
 
        for (y = rect->y1; y < rect->y2; y++) {
-               pix32 = src + (y * fb->pitches[0]);
-               pix32 += rect->x1;
+               sbuf32 = src + (y * fb->pitches[0]);
+               sbuf32 += rect->x1;
 
                for (x = 0; x < width; x++) {
                        unsigned int pixpos = x % block_width; /* within byte from the left */
@@ -126,9 +127,10 @@ static size_t gud_xrgb8888_to_color(u8 *dst, const struct drm_format_info *forma
                                *block = 0;
                        }
 
-                       r = *pix32 >> 16;
-                       g = *pix32 >> 8;
-                       b = *pix32++;
+                       pix32 = le32_to_cpu(*sbuf32++);
+                       r = pix32 >> 16;
+                       g = pix32 >> 8;
+                       b = pix32;
 
                        switch (format->format) {
                        case GUD_DRM_FORMAT_XRGB1111: