[PATCH 6.12 475/567] drm/mgag200: Fix big-endian support

Greg Kroah-Hartman
2026-01-06T17:40:32Z

From: René Rebe <rene@exactco.de>

commit 6cb31fba137d45e682ce455b8ea364f44d5d4f98 upstream.

Unlike the original, deleted Matrox mga driver, the new mgag200 driver
has the XRGB frame-buffer byte swapped on big-endian "RISC"
systems. Fix by enabling byte swapping "PowerPC" OPMODE for any
__BIG_ENDIAN config.

Fixes: 414c45310625 ("mgag200: initial g200se driver (v2)")
Signed-off-by: René Rebe <rene@exactco.de>
Cc: stable@kernel.org
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patch.msgid.link/20251208.141827.965103015954471168.rene@exactco.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/mgag200/mgag200_mode.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -175,6 +175,30 @@ static void mgag200_set_startadd(struct
WREG_ECRT(0x00, crtcext0);
}

+/*
+ * Set the opmode for the hardware swapper for Big-Endian processor
+ * support for the frame buffer aperture and DMAWIN space.
+ */
+static void mgag200_set_datasiz(struct mga_device *mdev, u32 format)
+{
+#if defined(__BIG_ENDIAN)
+ u32 opmode = RREG32(MGAREG_OPMODE);
+
+ opmode &= ~(GENMASK(17, 16) | GENMASK(9, 8) | GENMASK(3, 2));
+
+ /* Big-endian byte-swapping */
+ switch (format) {
+ case DRM_FORMAT_RGB565:
+ opmode |= 0x10100;
+ break;
+ case DRM_FORMAT_XRGB8888:
+ opmode |= 0x20200;
+ break;
+ }
+ WREG32(MGAREG_OPMODE, opmode);
+#endif
+}
+
void mgag200_init_registers(struct mga_device *mdev)
{
u8 crtc11, misc;
@@ -510,6 +534,7 @@ void mgag200_primary_plane_helper_atomic
struct drm_atomic_helper_damage_iter iter;
struct drm_rect damage;

+ mgag200_set_datasiz(mdev, fb->format->format);
drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
drm_atomic_for_each_plane_damage(&iter, &damage) {
mgag200_handle_damage(mdev, shadow_plane_state->data, fb, &damage);