drm/ofdrm: Support big-endian scanout buffers

All DRM formats assume little-endian byte order. On big-endian systems,
it is likely that the scanout buffer is in big endian as well. Update
the format accordingly and add endianness conversion to the format-helper
library. Also opt-in to allocated buffers in host format by default.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221011150712.3928-6-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index e2f7662..653a582 100644 (file)
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -660,6 +660,11 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
                        drm_fb_xrgb8888_to_rgb565(dst, dst_pitch, src, fb, clip, false);
                        return 0;
                }
+       } else if (dst_format == (DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN)) {
+               if (fb_format == DRM_FORMAT_RGB565) {
+                       drm_fb_swab(dst, dst_pitch, src, fb, clip, false);
+                       return 0;
+               }
        } else if (dst_format == DRM_FORMAT_RGB888) {
                if (fb_format == DRM_FORMAT_XRGB8888) {
                        drm_fb_xrgb8888_to_rgb888(dst, dst_pitch, src, fb, clip);
@@ -678,6 +683,11 @@ int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t d
                        drm_fb_xrgb8888_to_xrgb2101010(dst, dst_pitch, src, fb, clip);
                        return 0;
                }
+       } else if (dst_format == DRM_FORMAT_BGRX8888) {
+               if (fb_format == DRM_FORMAT_XRGB8888) {
+                       drm_fb_swab(dst, dst_pitch, src, fb, clip, false);
+                       return 0;
+               }
        }
 
        drm_warn_once(fb->dev, "No conversion helper from %p4cc to %p4cc found.\n",

diff --git a/drivers/gpu/drm/tiny/ofdrm.c b/drivers/gpu/drm/tiny/ofdrm.c
index 3b0eaeb..0e1cc23 100644 (file)
--- a/drivers/gpu/drm/tiny/ofdrm.c
+++ b/drivers/gpu/drm/tiny/ofdrm.c
@@ -94,7 +94,7 @@ static int display_get_validated_int0(struct drm_device *dev, const char *name,
 }
 
 static const struct drm_format_info *display_get_validated_format(struct drm_device *dev,
-                                                                 u32 depth)
+                                                                 u32 depth, bool big_endian)
 {
        const struct drm_format_info *info;
        u32 format;
@@ -115,6 +115,29 @@ static const struct drm_format_info *display_get_validated_format(struct drm_dev
                return ERR_PTR(-EINVAL);
        }
 
+       /*
+        * DRM formats assume little-endian byte order. Update the format
+        * if the scanout buffer uses big-endian ordering.
+        */
+       if (big_endian) {
+               switch (format) {
+               case DRM_FORMAT_XRGB8888:
+                       format = DRM_FORMAT_BGRX8888;
+                       break;
+               case DRM_FORMAT_ARGB8888:
+                       format = DRM_FORMAT_BGRA8888;
+                       break;
+               case DRM_FORMAT_RGB565:
+                       format = DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN;
+                       break;
+               case DRM_FORMAT_XRGB1555:
+                       format = DRM_FORMAT_XRGB1555 | DRM_FORMAT_BIG_ENDIAN;
+                       break;
+               default:
+                       break;
+               }
+       }
+
        info = drm_format_info(format);
        if (!info) {
                drm_err(dev, "cannot find framebuffer format for depth %u\n", depth);
@@ -134,6 +157,23 @@ static int display_read_u32_of(struct drm_device *dev, struct device_node *of_no
        return ret;
 }
 
+static bool display_get_big_endian_of(struct drm_device *dev, struct device_node *of_node)
+{
+       bool big_endian;
+
+#ifdef __BIG_ENDIAN
+       big_endian = true;
+       if (of_get_property(of_node, "little-endian", NULL))
+               big_endian = false;
+#else
+       big_endian = false;
+       if (of_get_property(of_node, "big-endian", NULL))
+               big_endian = true;
+#endif
+
+       return big_endian;
+}
+
 static int display_get_width_of(struct drm_device *dev, struct device_node *of_node)
 {
        u32 width;
@@ -613,6 +653,7 @@ static void ofdrm_device_set_gamma_linear(struct ofdrm_device *odev,
 
        switch (format->format) {
        case DRM_FORMAT_RGB565:
+       case DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN:
                /* Use better interpolation, to take 32 values from 0 to 255 */
                for (i = 0; i < OFDRM_GAMMA_LUT_SIZE / 8; i++) {
                        unsigned char r = i * 8 + i / 4;
@@ -631,6 +672,7 @@ static void ofdrm_device_set_gamma_linear(struct ofdrm_device *odev,
                }
                break;
        case DRM_FORMAT_XRGB8888:
+       case DRM_FORMAT_BGRX8888:
                for (i = 0; i < OFDRM_GAMMA_LUT_SIZE; i++)
                        odev->funcs->cmap_write(odev, i, i, i, i);
                break;
@@ -650,6 +692,7 @@ static void ofdrm_device_set_gamma(struct ofdrm_device *odev,
 
        switch (format->format) {
        case DRM_FORMAT_RGB565:
+       case DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN:
                /* Use better interpolation, to take 32 values from lut[0] to lut[255] */
                for (i = 0; i < OFDRM_GAMMA_LUT_SIZE / 8; i++) {
                        unsigned char r = lut[i * 8 + i / 4].red >> 8;
@@ -668,6 +711,7 @@ static void ofdrm_device_set_gamma(struct ofdrm_device *odev,
                }
                break;
        case DRM_FORMAT_XRGB8888:
+       case DRM_FORMAT_BGRX8888:
                for (i = 0; i < OFDRM_GAMMA_LUT_SIZE; i++) {
                        unsigned char r = lut[i].red >> 8;
                        unsigned char g = lut[i].green >> 8;
@@ -718,6 +762,9 @@ static const uint32_t ofdrm_primary_plane_formats[] = {
        DRM_FORMAT_RGB565,
        //DRM_FORMAT_XRGB1555,
        //DRM_FORMAT_C8,
+       /* Big-endian formats below */
+       DRM_FORMAT_BGRX8888,
+       DRM_FORMAT_RGB565 | DRM_FORMAT_BIG_ENDIAN,
 };
 
 static const uint64_t ofdrm_primary_plane_format_modifiers[] = {
@@ -1051,6 +1098,7 @@ static struct ofdrm_device *ofdrm_device_create(struct drm_driver *drv,
        struct ofdrm_device *odev;
        struct drm_device *dev;
        enum ofdrm_model model;
+       bool big_endian;
        int width, height, depth, linebytes;
        const struct drm_format_info *format;
        u64 address;
@@ -1112,6 +1160,8 @@ static struct ofdrm_device *ofdrm_device_create(struct drm_driver *drv,
                break;
        }
 
+       big_endian = display_get_big_endian_of(dev, of_node);
+
        width = display_get_width_of(dev, of_node);
        if (width < 0)
                return ERR_PTR(width);
@@ -1125,7 +1175,7 @@ static struct ofdrm_device *ofdrm_device_create(struct drm_driver *drv,
        if (linebytes < 0)
                return ERR_PTR(linebytes);
 
-       format = display_get_validated_format(dev, depth);
+       format = display_get_validated_format(dev, depth, big_endian);
        if (IS_ERR(format))
                return ERR_CAST(format);
        if (!linebytes) {
@@ -1237,6 +1287,7 @@ static struct ofdrm_device *ofdrm_device_create(struct drm_driver *drv,
                dev->mode_config.preferred_depth = depth;
                break;
        }
+       dev->mode_config.quirk_addfb_prefer_host_byte_order = true;
 
        /* Primary plane */