[PATCH] fbdev: atafb: Restrict SuperVidel handling to the Falcon

[PATCH] fbdev: atafb: Restrict SuperVidel handling to the Falcon

[Miro Kropacek]

A framebuffer at 0xa0000000 or above is taken as being in SuperVidel
RAM. A TT with a VME graphics card such as the Nova has its framebuffer
there too, so in 8bpp it gets the Falcon palette registers instead of
the card's VGA DAC, and in 8, 16 and 32bpp the SuperBlitter, which it
does not have.

The SuperVidel exists only for the Falcon, so check for the Falcon video
hardware as well.

Fixes: 51df976c3268 ("fbdev: atafb: Add support for further video bit depths on atafb:external")
Fixes: d463633d63e6 ("fbdev: atafb: Add support for SuperVidel's SuperBlitter")
Cc: stable@vger.kernel.org
Reported-by: Christian Zietz <czietz@gmx.net>
Signed-off-by: Miro Kropacek <miro.kropacek@gmail.com>
---
 drivers/video/fbdev/atafb.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/video/fbdev/atafb.c b/drivers/video/fbdev/atafb.c
index c32576cb1720..5d9265caa9ab 100644
--- a/drivers/video/fbdev/atafb.c
+++ b/drivers/video/fbdev/atafb.c
@@ -2065,6 +2065,15 @@ static void st_ovsc_switch(void)
 
 #ifdef ATAFB_EXT
 
+/*
+ * Only a Falcon can have a SuperVidel; a TT with a VME graphics card can
+ * have its framebuffer in the same address range.
+ */
+static bool ext_is_supervidel(void)
+{
+	return ATARIHW_PRESENT(VIDEL_SHIFTER) && external_addr >= 0xa0000000;
+}
+
 static int ext_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
 {
 	strcpy(fix->id, "Unknown Extern");
@@ -2083,8 +2092,7 @@ static int ext_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
 		 * SuperVidel 8bpp chunky (fb in SV RAM) uses the Falcon palette
 		 */
 		int visual = (external_vgaiobase ||
-			      (external_depth == 8 &&
-			       external_addr >= 0xa0000000)) ?
+			      (external_depth == 8 && ext_is_supervidel())) ?
 					 FB_VISUAL_PSEUDOCOLOR :
 					 FB_VISUAL_STATIC_PSEUDOCOLOR;
 		switch (external_pmode) {
@@ -2181,7 +2189,7 @@ static int ext_encode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
 		var->transp.offset = 24;
 		var->transp.length = 8;
 	} else if (external_pmode == FB_TYPE_PACKED_PIXELS &&
-		   external_depth == 8 && external_addr >= 0xa0000000) {
+		   external_depth == 8 && ext_is_supervidel()) {
 		/* SuperVidel 8bpp chunky: palette has 8 bits per channel.
 		 * Without this, fb_get_color_depth() sees length 0 and
 		 * fbcon falls back to its 2-color palette — the console
@@ -2245,7 +2253,7 @@ static int ext_setcolreg(unsigned int regno, unsigned int red,
 		return 0;
 	}
 	if (external_pmode == FB_TYPE_PACKED_PIXELS && external_depth == 8 &&
-	    external_addr >= 0xa0000000) {
+	    ext_is_supervidel()) {
 		/* SuperVidel native 8bpp chunky scans out via the Falcon
 		 * palette registers, honoring all 8 bits per channel
 		 */
@@ -3336,7 +3344,7 @@ static int __init atafb_probe(struct platform_device *pdev)
 		memset (screen_base, 0, external_len);
 
 		/* framebuffer in SV RAM: enable the SuperBlitter */
-		if (external_addr >= 0xa0000000 &&
+		if (ext_is_supervidel() &&
 		    ((external_pmode == FB_TYPE_PACKED_PIXELS &&
 		      external_depth == 8) ||
 		     (external_pmode == -1 &&
-- 
2.43.0