[U-Boot] [PATCH v3 1/2] drivers/video/am335x-fb: Add support for 16bpp format

[Hannes Schmelzer <hannes@schmelzer.or.at>]

On 27.04.2016 21:39, Martin Pietryka wrote:
> To support 16bpp we just need to change the raster_ctrl register
> accordingly. Also 32bpp mode should work as well, but was not tested.
> According to the TRM the uppermost byte will be ignored when
> LCD_TFT_24BPP_UNPACK is set.
>
> The switch logic is based on the Liunx kernel tilcdc driver:
> drivers/gpu/drm/tilcdc/tilcdc_crtc.c: lines 407 through 419
> (kernel was checked out at commit: bcc981e9ed8)
>
> Signed-off-by: Martin Pietryka <martin.pietryka@chello.at>
> ---
>
> Changes in v3:
> - Moved switch statement before changing any registers
>
>   drivers/video/am335x-fb.c | 22 +++++++++++++++++++---
>   1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/video/am335x-fb.c b/drivers/video/am335x-fb.c
> index 0ec843f..d984435 100644
> --- a/drivers/video/am335x-fb.c
> +++ b/drivers/video/am335x-fb.c
> @@ -5,7 +5,7 @@
>    * minimal framebuffer driver for TI's AM335x SoC to be compatible with
>    * Wolfgang Denk's LCD-Framework (CONFIG_LCD, common/lcd.c)
>    *
> - * - supporting only 24bit RGB/TFT raster Mode (not using palette)
> + * - supporting 16/24/32bit RGB/TFT raster Mode (not using palette)
>    * - sets up LCD controller as in 'am335x_lcdpanel' struct given
>    * - starts output DMA from gd->fb_base buffer
>    *
> @@ -106,6 +106,8 @@ int lcd_get_size(int *line_length)
>   
>   int am335xfb_init(struct am335x_lcdpanel *panel)
>   {
> +	u32 raster_ctrl = 0;
> +
>   	if (0 == gd->fb_base) {
>   		printf("ERROR: no valid fb_base stored in GLOBAL_DATA_PTR!\n");
>   		return -1;
> @@ -115,6 +117,21 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
>   		return -1;
>   	}
>   
> +	/* We can already set the bits for the raster_ctrl in this check */
> +	switch (panel->bpp) {
> +	case 16:
> +		break;
> +	case 32:
> +		raster_ctrl |= LCD_TFT_24BPP_UNPACK;
> +		/* fallthrough */
> +	case 24:
> +		raster_ctrl |= LCD_TFT_24BPP_MODE;
> +		break;
> +	default:
> +		error("am335x-fb: invalid bpp value: %d\n", panel->bpp);
> +		return -1;
> +	}
> +
>   	debug("setting up LCD-Controller for %dx%dx%d (hfp=%d,hbp=%d,hsw=%d / ",
>   	      panel->hactive, panel->vactive, panel->bpp,
>   	      panel->hfp, panel->hbp, panel->hsw);
> @@ -157,8 +174,7 @@ int am335xfb_init(struct am335x_lcdpanel *panel)
>   				LCD_HBPMSB(panel->hbp) |
>   				LCD_HFPMSB(panel->hfp) |
>   				0x0000FF00;	/* clk cycles for ac-bias */
> -	lcdhw->raster_ctrl =	LCD_TFT_24BPP_MODE |
> -				LCD_TFT_24BPP_UNPACK |
> +	lcdhw->raster_ctrl =	raster_ctrl |
>   				LCD_PALMODE_RAWDATA |
>   				LCD_TFT_MODE |
>   				LCD_RASTER_ENABLE;
Reviewed-by: Hannes Schmelzer <oe5hpm@oevsv.at>
Tested-by: Hannes Schmelzer <oe5hpm@oevsv.at>