Re: [PATCH] drm/mgag200: fix big-endian support

[Thomas Zimmermann]

Hi,

let's first go through the ast patch. Most of that review also applies 
to this driver.

Best regards
Thomas

Am 02.12.25 um 16:42 schrieb René Rebe:
Unlike the original deleted Matrox mga driver, the new mgag200 driver
has the frame-buffer RGBX 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 <r...@exactco.de>
---
Tested on IBM 43p Model 150 (7043-150) running T2/Linux.
---
  drivers/gpu/drm/mgag200/mgag200_mode.c | 14 ++++++++++++++
  1 file changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c 
b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 951d715dea30..9073063f6473 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -655,6 +655,20 @@ void mgag200_crtc_helper_atomic_enable(struct drm_crtc 
*crtc, struct drm_atomic_
        else
                mgag200_crtc_fill_gamma(mdev, format);
  
+#ifdef __BIG_ENDIAN
+       /* Big-endian byte-swapping */
+       switch (format->format) {
+       case DRM_FORMAT_RGB565:
+               WREG32(MGAREG_OPMODE, 1 << 16);
+               break;
+       case DRM_FORMAT_XRGB8888:
+               WREG32(MGAREG_OPMODE, 2 << 16);
+               break;
+       default:
+               break;
+       }
+#endif
+
        mgag200_enable_display(mdev);
  }
  

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, Werner Knoblich, (HRB 36809, AG Nürnberg)