video: ARM CLCD: support pads connected in reverse order

There are CLCDs connected with the pads in BGR rather than RGB
order. It really doesn't matter since the CLCD has a flag and
a bit to switch the position of the RGB and BGR components.
This is needed to put something logical into the
arm,pl11x,tft-r0g0b0-pads property of the device tree on the
Nomadik which will then be <16 8 0>.

Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/include/linux/amba/clcd.h b/include/linux/amba/clcd.h
index e64c1ccebb76..8b64ec0d574b 100644
--- a/include/linux/amba/clcd.h
+++ b/include/linux/amba/clcd.h
@@ -108,6 +108,12 @@ struct clcd_panel {
                                 grayscale:1;
         unsigned int            connector;
         struct backlight_device *backlight;
+        /*
+         * If the B/R lines are switched between the CLCD
+         * and the panel we need to know this and not try to
+         * compensate with the BGR bit in the control register.
+         */
+        bool                    bgr_connection;
 };
 
 struct clcd_regs {
@@ -234,16 +240,22 @@ static inline void clcdfb_decode(struct clcd_fb *fb, struct clcd_regs *regs)
         if (var->grayscale)
                 val |= CNTL_LCDBW;
 
-        if (fb->panel->caps && fb->board->caps &&
-            var->bits_per_pixel >= 16) {
+        if (fb->panel->caps && fb->board->caps && var->bits_per_pixel >= 16) {
                 /*
                  * if board and panel supply capabilities, we can support
-                 * changing BGR/RGB depending on supplied parameters
+                 * changing BGR/RGB depending on supplied parameters. Here
+                 * we switch to what the framebuffer is providing if need
+                 * be, so if the framebuffer is BGR but the display connection
+                 * is RGB (first case) we switch it around. Vice versa mutatis
+                 * mutandis if the framebuffer is RGB but the display connection
+                 * is BGR, we flip it around.
                  */
                 if (var->red.offset == 0)
                         val &= ~CNTL_BGR;
                 else
                         val |= CNTL_BGR;
+                if (fb->panel->bgr_connection)
+                        val ^= CNTL_BGR;
         }
 
         switch (var->bits_per_pixel) {