[PATCH] atmel_lcdfb: wiring BGR to RGB color mode

[PATCH] atmel_lcdfb: wiring BGR to RGB color mode

[Nicolas Ferre]

Adds different wiring mode for the LCD screen.

The legacy atmel LCDC IP uses a non standard color mode,
"BGR-555.1" instead "RGB-565". The major part of graphic stacks 
for embedded systems uses only "RGB-565". It is possible to swap 
LCD IOs instead of doing this bit swapping by software (See 
application note AT91SAM9 LCD Controller
http://www.atmel.com/dyn/resources/prod_documents/doc6300.pdf)

This wire swapping is done on the at91sam9rl-ek board (board code 
using this patch will come later).
---
 drivers/video/atmel_lcdfb.c |   27 ++++++++++++++++++++++-----
 include/video/atmel_lcdc.h  |   10 ++++++++++
 2 files changed, 32 insertions(+), 5 deletions(-)

--- linux-2.6.x-rc.orig/drivers/video/atmel_lcdfb.c
+++ linux-2.6.x-rc/drivers/video/atmel_lcdfb.c
@@ -338,19 +338,35 @@ static int atmel_lcdfb_check_var(struct 
 		break;
 	case 15:
 	case 16:
-		var->red.offset = 0;
+		if (sinfo->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
+			/* RGB:565 mode */
+			var->red.offset = 11;
+			var->blue.offset = 0;
+			var->green.length = 6;
+		} else {
+			/* BGR:555 mode */
+			var->red.offset = 0;
+			var->blue.offset = 10;
+			var->green.length = 5;
+		}
 		var->green.offset = 5;
-		var->blue.offset = 10;
-		var->red.length = var->green.length = var->blue.length = 5;
+		var->red.length = var->blue.length = 5;
 		break;
 	case 32:
 		var->transp.offset = 24;
 		var->transp.length = 8;
 		/* fall through */
 	case 24:
-		var->red.offset = 0;
+		if (sinfo->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
+			/* RGB:888 mode */
+			var->red.offset = 16;
+			var->blue.offset = 0;
+		} else {
+			/* BGR:888 mode */
+			var->red.offset = 0;
+			var->blue.offset = 16;
+		}
 		var->green.offset = 8;
-		var->blue.offset = 16;
 		var->red.length = var->green.length = var->blue.length = 8;
 		break;
 	default:
@@ -697,6 +713,7 @@ static int __init atmel_lcdfb_probe(stru
 		sinfo->atmel_lcdfb_power_control = pdata_sinfo->atmel_lcdfb_power_control;
 		sinfo->guard_time = pdata_sinfo->guard_time;
 		sinfo->lcdcon_is_backlight = pdata_sinfo->lcdcon_is_backlight;
+		sinfo->lcd_wiring_mode = pdata_sinfo->lcd_wiring_mode;
 	} else {
 		dev_err(dev, "cannot get default configuration\n");
 		goto free_info;
--- linux-2.6.x-rc.orig/include/video/atmel_lcdc.h
+++ linux-2.6.x-rc/include/video/atmel_lcdc.h
@@ -22,6 +22,15 @@
 #ifndef __ATMEL_LCDC_H__
 #define __ATMEL_LCDC_H__
 
+
+/* Way LCD wires are connected to the chip:
+ * Some Atmel chips use BGR color mode (instead of standard RGB)
+ * A swapped wiring onboard can bring to RGB mode.
+ */
+#define ATMEL_LCDC_WIRING_BGR	0
+#define ATMEL_LCDC_WIRING_RGB	1
+
+
  /* LCD Controller info data structure, stored in device platform_data */
 struct atmel_lcdfb_info {
 	spinlock_t		lock;
@@ -42,6 +51,7 @@ struct atmel_lcdfb_info {
 	u8			saved_lcdcon;
 
 	u8			default_bpp;
+	u8			lcd_wiring_mode;
 	unsigned int		default_lcdcon2;
 	unsigned int		default_dmacon;
 	void (*atmel_lcdfb_power_control)(int on);

Re: [Linux-fbdev-devel] [PATCH] atmel_lcdfb: wiring BGR to RGB colormode

[Nicolas Ferre]

Nicolas Ferre :
> Adds different wiring mode for the LCD screen.
> 
> The legacy atmel LCDC IP uses a non standard color mode,
> "BGR-555.1" instead "RGB-565". The major part of graphic stacks 
> for embedded systems uses only "RGB-565". It is possible to swap 
> LCD IOs instead of doing this bit swapping by software (See 
> application note AT91SAM9 LCD Controller
> http://www.atmel.com/dyn/resources/prod_documents/doc6300.pdf)
> 
> This wire swapping is done on the at91sam9rl-ek board (board code 
> using this patch will come later).

Forgotten line :

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>


> ---
>  drivers/video/atmel_lcdfb.c |   27 ++++++++++++++++++++++-----
>  include/video/atmel_lcdc.h  |   10 ++++++++++
>  2 files changed, 32 insertions(+), 5 deletions(-)


-- 
Nicolas Ferre

Re: [PATCH] atmel_lcdfb: wiring BGR to RGB color mode

[Haavard Skinnemoen]

On Mon, 10 Mar 2008 15:26:18 +0100
Nicolas Ferre <nicolas.ferre@atmel.com> wrote:

> The legacy atmel LCDC IP uses a non standard color mode,
> "BGR-555.1" instead "RGB-565". The major part of graphic stacks 
> for embedded systems uses only "RGB-565". It is possible to swap 
> LCD IOs instead of doing this bit swapping by software (See 
> application note AT91SAM9 LCD Controller
> http://www.atmel.com/dyn/resources/prod_documents/doc6300.pdf)

> -		var->red.offset = 0;
> +		if (sinfo->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
> +			/* RGB:888 mode */
> +			var->red.offset = 16;
> +			var->blue.offset = 0;
> +		} else {
> +			/* BGR:888 mode */
> +			var->red.offset = 0;
> +			var->blue.offset = 16;
> +		}

Does RGB:565 always imply RGB:888 and vice versa?

If not, I think it would be better with separate flags for the possible
wirings:
   * 18-bit BGR-555.1 / 24-bit BGR-888
   * 16-bit RGB-565
   * 24-bit RGB-888

Or maybe I misunderstand something?

Haavard