Hi Ranga,
On 03.01.19 09:24, galla rao wrote:
Video Mode in Coreboot
*CorebootLog* coreboot video frame buffer information physical_address: 0xC0000000 *x_resolution: 0x400* *y_resolution: 0x300*
0x400 x 0x300 is exactly 1024x768.
bits_per_pixel: 0x20 bytes_per_line: 0x1000 red_mask_size: 0x8 red_mask_pos: 0x10
GOP UEFI driver (Tiano payload) is expected to report 4 modes GOP should report MaxMode 4 *0: 1600x900 BGRReserved Pixels 1600 1: 640x480 BGRReserved Pixels 640 2: 800x600 BGRReserved Pixels 800 3: 1024x768 BGRReserved Pixels 1024
Unlike legacy firmware, coreboot doesn't stay active after handing execution over to its payload. So there is no coreboot code that could change to a different mode afterwards. If you have to switch modes in Tianocore, you should disable the coreboot framebuffer and add a GOP driver to Tianocore instead.
With open-source graphics init, you could also set a fixed mode in coreboot. Alas, there is no open-source solution for Bay Trail that I know of. Though, existing solutions (e.g. libgfxinit) for other Intel platforms could be extended for Bay Trail (and could also be used to write an open-source GOP driver).
Nico