[PATCH] video: ARM CLCD: runtime check for Versatile

The current compile-time check for inversed IENB/CNTL does not
work in multiplatform boots: as soon as versatile is included
in the build, the IENB/CNTL is switched and breaks graphics.
Convert this to a runtime switch.

Cc: stable@vger.kernel.org
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <redacted>
Fixes: a29da136de34 ("ARM: versatile: convert to multi-platform")
Signed-off-by: Linus Walleij <redacted>
---
 drivers/video/fbdev/amba-clcd.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/video/fbdev/amba-clcd.c b/drivers/video/fbdev/amba-clcd.c
index 9362424c2340..f9ef06d0cd48 100644
--- a/drivers/video/fbdev/amba-clcd.c
+++ b/drivers/video/fbdev/amba-clcd.c

@@ -440,13 +440,14 @@ static int clcdfb_register(struct clcd_fb *fb)
 		fb->off_ienb = CLCD_PL111_IENB;
 		fb->off_cntl = CLCD_PL111_CNTL;
 	} else {
-#ifdef CONFIG_ARCH_VERSATILE
-		fb->off_ienb = CLCD_PL111_IENB;
-		fb->off_cntl = CLCD_PL111_CNTL;
-#else
-		fb->off_ienb = CLCD_PL110_IENB;
-		fb->off_cntl = CLCD_PL110_CNTL;
-#endif
+		if (of_machine_is_compatible("arm,versatile-ab") ||
+		    of_machine_is_compatible("arm,versatile-pb")) {
+			fb->off_ienb = CLCD_PL111_IENB;
+			fb->off_cntl = CLCD_PL111_CNTL;
+		} else {
+			fb->off_ienb = CLCD_PL110_IENB;
+			fb->off_cntl = CLCD_PL110_CNTL;
+		}
 	}
 
 	fb->clk = clk_get(&fb->dev->dev, NULL);

-- 
2.4.3

On Tuesday 02 February 2016 21:47:39 Linus Walleij wrote:

        } else {
-#ifdef CONFIG_ARCH_VERSATILE
-               fb->off_ienb = CLCD_PL111_IENB;
-               fb->off_cntl = CLCD_PL111_CNTL;
-#else
-               fb->off_ienb = CLCD_PL110_IENB;
-               fb->off_cntl = CLCD_PL110_CNTL;
-#endif
+               if (of_machine_is_compatible("arm,versatile-ab") ||
+                   of_machine_is_compatible("arm,versatile-pb")) {
+                       fb->off_ienb = CLCD_PL111_IENB;
+                       fb->off_cntl = CLCD_PL111_CNTL;
+               } else {
+                       fb->off_ienb = CLCD_PL110_IENB;
+                       fb->off_cntl = CLCD_PL110_CNTL;
+               }
        }

Could that be done based on the AMBA device ID instead?

	Arnd

On Tue, Feb 02, 2016 at 10:10:49PM +0100, Arnd Bergmann wrote:

On Tuesday 02 February 2016 21:47:39 Linus Walleij wrote:

quoted

        } else {
-#ifdef CONFIG_ARCH_VERSATILE
-               fb->off_ienb = CLCD_PL111_IENB;
-               fb->off_cntl = CLCD_PL111_CNTL;
-#else
-               fb->off_ienb = CLCD_PL110_IENB;
-               fb->off_cntl = CLCD_PL110_CNTL;
-#endif
+               if (of_machine_is_compatible("arm,versatile-ab") ||
+                   of_machine_is_compatible("arm,versatile-pb")) {
+                       fb->off_ienb = CLCD_PL111_IENB;
+                       fb->off_cntl = CLCD_PL111_CNTL;
+               } else {
+                       fb->off_ienb = CLCD_PL110_IENB;
+                       fb->off_cntl = CLCD_PL110_CNTL;
+               }
        }

Could that be done based on the AMBA device ID instead?

Unfortunately not.  It's a mistake made on one Versatile board
which reverses the registers.  There's nothing to distinguish it
in the primecell itself.

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.

On Wednesday 03 February 2016 00:41:54 Russell King - ARM Linux wrote:

On Tue, Feb 02, 2016 at 10:10:49PM +0100, Arnd Bergmann wrote:

quoted

On Tuesday 02 February 2016 21:47:39 Linus Walleij wrote:

quoted

        } else {
-#ifdef CONFIG_ARCH_VERSATILE
-               fb->off_ienb = CLCD_PL111_IENB;
-               fb->off_cntl = CLCD_PL111_CNTL;
-#else
-               fb->off_ienb = CLCD_PL110_IENB;
-               fb->off_cntl = CLCD_PL110_CNTL;
-#endif
+               if (of_machine_is_compatible("arm,versatile-ab") ||
+                   of_machine_is_compatible("arm,versatile-pb")) {
+                       fb->off_ienb = CLCD_PL111_IENB;
+                       fb->off_cntl = CLCD_PL111_CNTL;
+               } else {
+                       fb->off_ienb = CLCD_PL110_IENB;
+                       fb->off_cntl = CLCD_PL110_CNTL;
+               }
        }

Could that be done based on the AMBA device ID instead?

Unfortunately not.  It's a mistake made on one Versatile board
which reverses the registers.  There's nothing to distinguish it
in the primecell itself.

Ok, I see. It would be nice to have this knowledge locally in
the driver, e.g. through a special compatible string for the
variant on the versatile, or a bool property, but this way seems
good enough as we can be reasonably sure that nobody else made the
same mistake.

	Arnd