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

Hannes Schmelzer
2016-04-27T09:16:05Z

On 04/27/2016 01:21 AM, 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>
> ---
> drivers/video/am335x-fb.c | 29 +++++++++++++++++++++++------
> 1 file changed, 23 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/video/am335x-fb.c b/drivers/video/am335x-fb.c
> index 0ec843f..f2b4c78 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;
> @@ -157,11 +159,26 @@ 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 |
> - LCD_PALMODE_RAWDATA |
> - LCD_TFT_MODE |
> - LCD_RASTER_ENABLE;
> +
> + raster_ctrl = LCD_PALMODE_RAWDATA |
> + LCD_TFT_MODE |
> + LCD_RASTER_ENABLE;
> +
> + 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;
please return -1 on error;
I would also suggest to put this switch case above the first hw-access
or doing anything on lcd,
so the controller and display leaves untouched on wrong parameters.
> + }
> +
> + lcdhw->raster_ctrl = raster_ctrl;
>
> gd->fb_base += 0x20; /* point fb behind palette */
>
best regards,
Hannes