The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 6cb31fba137d45e682ce455b8ea364f44d5d4f98 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2026010546-doorpost-resume-e2e2@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6cb31fba137d45e682ce455b8ea364f44d5d4f98 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ren=C3=A9=20Rebe?= rene@exactco.de Date: Mon, 8 Dec 2025 14:18:27 +0100 Subject: [PATCH] drm/mgag200: Fix big-endian support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index 951d715dea30..d019177462cf 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -161,6 +161,30 @@ static void mgag200_set_startadd(struct mga_device *mdev, 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; @@ -496,6 +520,7 @@ void mgag200_primary_plane_helper_atomic_update(struct drm_plane *plane, 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);