On Wed, 31 Dec 2014 12:22:17 +0100 Hans de Goede hdegoede@redhat.com wrote:
On 30-12-14 13:17, Siarhei Siamashka wrote:
On Tue, 30 Dec 2014 11:26:51 +0100 Hans de Goede hdegoede@redhat.com wrote:
Currently basically only lcd_if = 0 and lcd_frm = 1 are supported, it should be possible to add support for other lcd_frm = x values easily, so if you encounter those let me know, lcd_if != 0 is going to be much harder to support and currently is not on my schedule.
It's all in the orange part of the table at the bottom. The lcd_frm = 0 seems to be relatively common. The links to FEX files for each device are also there in the table and can be used to confirm the details.
The http://linux-sunxi.org/Wexler_TAB_7200 tablet with its fex file https://github.com/linux-sunxi/sunxi-boards/blob/master/sys_config/a20/wexle... is one of the examples.
Ok, so I've looked this up in the linux-sunxi code again to freshen my memory, and grepping that code gives this:
drivers/video/sunxi/disp/ebios_lcdc_tve.h 51: LCDC_FRM_RGB888 = 0, 52: LCDC_FRM_RGB666 = 1, 53: LCDC_FRM_RGB656 = 2,
All 3 of which are already supported (but other then LCDC_FRM_RGB666 untested) in the u-boot lcd code :
LCDC_FRM_RGB888 -> depth:24 LCDC_FRM_RGB666 -> depth:18 LCDC_FRM_RGB656 -> depth:17So this results in the following translation:
lcd_frm = 0 -> depth:24 lcd_frm = 1 -> depth:18 lcd_frm = 2 -> depth:17
In fact the 'lcd_frm' FEX option only controls dithering. The color depth is controlled by the 'lcd_cpu_if' FEX option. These color depth settings end up in the TCON0_CPU_IF_REG register, and your LCD patches currently unconditionally set it to 18-bit depth anyway.
There is also a wiki page, describing FEX settings with a lot of useful information there: http://linux-sunxi.org/Fex_Guide#lcd.5B0.2F1.5D_configuration
As for the dithering settings, you can try to compare the results of having "depth:0" vs. "depth:18" in CONFIG_VIDEO_LCD_MODE and using the following simple test program.
With "depth:0", the picture looks correct, but blocky (6 bits per color component is not great for gradients without dithering). With "depth:18", the picture looks smooth.
/******** Display a gradient picture ************/ #include <stdint.h> #include <stdio.h> #include <fcntl.h> #include <linux/fb.h> #include <sys/ioctl.h> #include <sys/mman.h>
int main() { int fd, x, y; uint32_t *fb; struct fb_fix_screeninfo finfo; struct fb_var_screeninfo vinfo;
if ((fd = open("/dev/fb0", O_RDWR)) == -1) { printf("Can't open /dev/fb0\n"); return 1; }
if (ioctl(fd, FBIOGET_FSCREENINFO, &finfo)) { printf("FBIOGET_FSCREENINFO failed\n"); return 1; }
if (ioctl(fd, FBIOGET_VSCREENINFO, &vinfo)) { printf("FBIOGET_VSCREENINFO failed\n"); return 1; }
if (vinfo.bits_per_pixel != 32) { printf("Only 32bpp framebuffer is supported\n"); return 1; }
fb = mmap(0, finfo.smem_len, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (fb == (void *)-1) { printf("mmap failed\n"); return 1; }
for (y = 0; y < vinfo.yres; y++) for (x = 0; x < vinfo.xres; x++) fb[y * vinfo.xres + x] = (255 * x / vinfo.xres) * 0x000100 + (255 * y / vinfo.yres) * 0x010001;
return 0; } /************************************************/
So "lcd_frm = 0" is not expected to cause any problems and is already supported. But naming and meaning of the options in the CONFIG_VIDEO_LCD_MODE string could be improved.
I just wonder why there are so many FEX files with lcd_frm = 0. It does not seem to be a great idea, unless there is some good reason.