[OpenBIOS] [PATCH 14/20] sbus.c: fix TCX24 initialisation

[Mark Cave-Ayland]

Even though we boot in 24-bit enabled mode, OpenBIOS only uses the 8-bit
framebuffer. Hence we need to override the depth/linebytes obtained from
QEMU to force the graphics subsystem into 8-bit mode, which was what seems
to have been happening before this patch series.

Note: it seems strange that we have to update the package linebytes
property too, however Debian etch freezes if we don't set it to match the
8-bit framebuffer even though it correctly switches to 24-bit mode.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland at ilande.co.uk>
---
 openbios-devel/drivers/sbus.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/openbios-devel/drivers/sbus.c b/openbios-devel/drivers/sbus.c
index fbac2d7..8cc0bf9 100644
--- a/openbios-devel/drivers/sbus.c
+++ b/openbios-devel/drivers/sbus.c
@@ -17,6 +17,7 @@
 #include "libc/vsprintf.h"
 #include "drivers/drivers.h"
 #include "libopenbios/ofmem.h"
+#include "libopenbios/video.h"
 
 #define SBUS_REGS        0x28
 #define SBUS_SLOTS       16
@@ -329,6 +330,17 @@ ob_tcx_init(unsigned int slot, const char *path)
         fword("property");
     }
 
+    /* Even with a 24-bit enabled TCX card, the control plane is
+       used in 8-bit mode. So force the video subsystem into 8-bit
+       mode before initialisation. */
+    if (graphic_depth == 24) {
+        VIDEO_DICT_VALUE(video.depth) = 8;
+        VIDEO_DICT_VALUE(video.rb) = VIDEO_DICT_VALUE(video.w);
+
+        chosen = get_cur_dev();
+        set_int_property(chosen, "linebytes", VIDEO_DICT_VALUE(video.rb));
+    }
+
     bind_func("hw-set-color", tcx_hw_set_color);
     feval("['] qemu-tcx-driver-init is-install");
 
-- 
1.7.10.4