drm/format-helper: Implement drm_fb_swab() with per-line helpers

Replace the inner loop of drm_fb_swab() with helper functions that
swap the bytes in each pixel. This will allow to share the outer
loop with other conversion helpers.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220427141409.22842-2-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 34b7ef4..f704993 100644 (file)
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -100,6 +100,26 @@ void drm_fb_memcpy_toio(void __iomem *dst, unsigned int dst_pitch, const void *v
 }
 EXPORT_SYMBOL(drm_fb_memcpy_toio);
 
+static void drm_fb_swab16_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+       u16 *dbuf16 = dbuf;
+       const u16 *sbuf16 = sbuf;
+       const u16 *send16 = sbuf16 + pixels;
+
+       while (sbuf16 < send16)
+               *dbuf16++ = swab16(*sbuf16++);
+}
+
+static void drm_fb_swab32_line(void *dbuf, const void *sbuf, unsigned int pixels)
+{
+       u32 *dbuf32 = dbuf;
+       const u32 *sbuf32 = sbuf;
+       const u32 *send32 = sbuf32 + pixels;
+
+       while (sbuf32 < send32)
+               *dbuf32++ = swab32(*sbuf32++);
+}
+
 /**
  * drm_fb_swab - Swap bytes into clip buffer
  * @dst: Destination buffer
@@ -120,12 +140,11 @@ void drm_fb_swab(void *dst, unsigned int dst_pitch, const void *src,
                 bool cached)
 {
        u8 cpp = fb->format->cpp[0];
-       size_t len = drm_rect_width(clip) * cpp;
-       const u16 *src16;
-       const u32 *src32;
-       u16 *dst16;
-       u32 *dst32;
-       unsigned int x, y;
+       unsigned long linepixels = drm_rect_width(clip);
+       size_t len = linepixels * cpp;
+       const void *sbuf;
+       void *dbuf;
+       unsigned int y;
        void *buf = NULL;
 
        if (WARN_ON_ONCE(cpp != 2 && cpp != 4))
@@ -133,31 +152,22 @@ void drm_fb_swab(void *dst, unsigned int dst_pitch, const void *src,
 
        if (!dst_pitch)
                dst_pitch = len;
+       src += clip_offset(clip, fb->pitches[0], cpp);
 
        if (!cached)
                buf = kmalloc(len, GFP_KERNEL);
 
-       src += clip_offset(clip, fb->pitches[0], cpp);
-
        for (y = clip->y1; y < clip->y2; y++) {
-               if (buf) {
-                       memcpy(buf, src, len);
-                       src16 = buf;
-                       src32 = buf;
-               } else {
-                       src16 = src;
-                       src32 = src;
-               }
-
-               dst16 = dst;
-               dst32 = dst;
+               if (buf)
+                       sbuf = memcpy(buf, src, len);
+               else
+                       sbuf = src;
+               dbuf = dst + clip->x1 * cpp;
 
-               for (x = clip->x1; x < clip->x2; x++) {
-                       if (cpp == 4)
-                               *dst32++ = swab32(*src32++);
-                       else
-                               *dst16++ = swab16(*src16++);
-               }
+               if (cpp == 4)
+                       drm_fb_swab32_line(dbuf, sbuf, linepixels);
+               else
+                       drm_fb_swab16_line(dbuf, sbuf, linepixels);
 
                src += fb->pitches[0];
                dst += dst_pitch;